sanitation

Sanitation

Chapter 10

10

TABLE OF CONTENTS

SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Sanitation improvement must be demand-responsive, and supported by an intensive health andhygiene programme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Community participation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Integrated planning and development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Sanitation is about environment and health . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Basic sanitation is a human right . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

The provision of access to sanitation services is a local government responsibility . . . . . . . . . . . . . . . . 2

Health for all rather than all for some . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Equitable regional allocation of development resources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Water has an economic value. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

The polluter pays principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Sanitation services must be financially sustainable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Environmental integrity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

PLANNING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

HYGIENE IN SANITATION PROJECTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

TECHNICAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Categories of sanitation systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Description of sanitation systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

FACTORS AFFECTING THE CHOICE OF A SANITATION SYSTEM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

General considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

The cost of the system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Sanitation at public facilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

DISPOSAL OF SLUDGE FROM ON-SITE SANITATION SYSTEMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Composition of pit or vault contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Methods of emptying pits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Sludge flow properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Vacuum tankers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Disposal of sludge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

i

GUIDELINES FOR HUMAN SETTLEMENT PLANNING AND DESIGN

Sanitation Chapter 10Revised August 2003

ii


Chapter 10 Sanitation

EVALUATION OF SITES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Topographical evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Soil profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Percolation capacity of the site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

POLLUTION CAUSED BY SANITATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Surface pollution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Groundwater pollution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

SULLAGE (GREYWATER) DISPOSAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Volumes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Health aspects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Disposal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Disposal systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Sullage treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

TOILET PEDESTALS AND SQUATTING PLATES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

DESIGN OF VIP TOILETS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

TOILET FACILITIES FOR PHYSICALLY DISABLED PERSONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

TRAINING OF MAINTENANCE WORKERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

UPGRADING OF SANITATION FACILITIES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

OFF-SITE WASTEWATER TREATMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Pond systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Package purification units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

APPENDIX A: INFORMATION REQUIRED FOR THE PLANNING AND DESIGN OF SANITATION PROJECTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

COMMUNITY MANAGEMENT APPROACH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Phase 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Phase 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Phase 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Phase 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Phase 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Phase 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Phase 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

HUMAN-RELATED DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Socio-cultural data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Community preferences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Economic and social conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Health and hygiene conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Institutional framework . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Environmental and technical aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

INFORMATION REQUIRED FOR POST-PROJECT EVALUATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

APPENDIX B: UPGRADING OF EXISTING SANITATION SYSTEMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

BASIC UPGRADING ALTERNATIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Alternative 1 - Aesthetic upgrading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Alternative 2 - Introduction of a water seal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Alternative 3 - Removal of liquids from the site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

UPGRADING ROUTES FOR THE VARIOUS SANITATION SYSTEMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Group 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Group 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Group 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Group 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

APPENDIX C: DESIGN GUIDELINES FOR WATERBORNE SANITATION SYSTEMS. . . . . . . . . . . . . . . . . . 28

SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

DESIGN CRITERIA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Design flows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Hydraulic design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Physical design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

MATERIALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Pipes and joints. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Manholes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Pumping installations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Pipework. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

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Sanitation Chapter 10

iv



Structural steelwork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Electrical installations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Other materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

GLOSSARY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

BIBLIOGRAPHY AND RECOMMENDED READING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

LIST OF TABLES

Table 10.1 Categories of sanitation systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Table 10.2 Sullage generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Table C.1 Average daily flows per single-family dwelling unit (du) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

Table C.2 Minimum sewer gradients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

Table C.3 Minimum internal dimensions of manhole chambers and shafts . . . . . . . . . . . . . . . . . . . . . . .32

v



vi



LIST OF FIGURES

Figure 10.1 Chemical toilet unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Figure 10.2 VIP toilet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Figure 10.3 VIDP toilet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Figure 10.4 Ventilated vault toilet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Figure 10.5 Urine-diversion toilet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Figure 10.6 Waterborne sewerage system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Figure 10.7 Shallow sewer system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Figure 10.8 Flushing toilet with conservancy tank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Figure 10.9 Settled sewage system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Figure 10.10 Flushing toilet with septic tank and soakaway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Figure 10.11 Aqua-privy toilet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

Figure 10.12 Minimum dimensions of a toilet room for physically disabled persons . . . . . . . . . . . . . . . . . .19

Figure C.1 Attenuation of peak flows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Figure C.2 Protection of pipes at reduced depths of cover (e.g. Class B bedding) . . . . . . . . . . . . . . . . . . .31

Figure C.3 Steep drops in sewers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

SCOPE

The guidelines for sanitation provision cover aspectsthat need to be considered when planning andimplementing sanitation projects for existingresidential areas and developing communities. Theguidelines will also be of assistance where the WaterServices Authority compiles a Water ServicesDevelopment Plan (the latter forms part of themunicipalitys Integrated Development Plan).

The guidelines will also assist in determining andsetting objectives, developing a strategy andidentifying the required planning activities forimplementing sanitation projects. Technical guidelinesare given for use in feasibility studies and the detaileddesign of sanitation provision.

The guidelines form part of a planned series ofmanagement guidelines intended for use by decisionmakers. The series of guidelines is shown in Table 9.1of Chapter 9: Water Supply.

INTRODUCTION

Water services (i.e. water supply and sanitation) inSouth Africa are controlled by the Water Services Act(Act 108 of 1997) and the National Water Act (Act 36of 1998). The Water Services Act deals with waterservices provision to consumers, while the NationalWater Act deals with water in its natural state.

As in the case of water supply, the provision ofsanitation to a community should take place in termsof the relevant Water Services Development Plan,which is required in terms of the Water Services Act.The Water Services Development Plan (which should,of course, be compiled taking cognisance of theNational Sanitation Policy) defines the minimum levelof sanitation as well as the desired level of sanitationfor communities that must be adhered to by a WaterServices Provider in its area of jurisdiction. It describesthe arrangements for water services provision in anarea, both present and future. Water services are alsoto be provided in accordance with regulationspublished in terms of the Water Services Act.

The provision of appropriate sanitation to acommunity should take place in accordance withnational policy. Among the major aims set out in theNational Sanitation Policy are the following:

to improve the health and quality of life of thewhole population;

to integrate the development of a community inthe provision of sanitation;

to protect the environment; and

to place the responsibility for household sanitationprovision with the family or household.

The minimum acceptable basic level of sanitation is(Department of Water Affairs & Forestry, 2001):

appropriate health and hygiene awareness andbehaviour;

a system for disposing of human excreta,householdwastewater and refuse, which is acceptable andaffordable to the users, safe, hygienic and easilyaccessible, and which does not have anunacceptable impact on the environment; and

a toilet facility for each household.

The safe disposal of human excreta alone does notnecessarily mean the creation of a healthyenvironment. Sanitation goes hand in hand with aneffective health-care programme. The importance ofeducation programmes should not be overlooked, andthe Department of Health is able to assist in this (referto the following section Hygiene in sanitationprojects).

Sanitation education is part of the National SanitationPolicy and should embrace proper health practices,such as personal hygiene, the need for all familymembers (including the children) to use the toilet andthe necessity of keeping the toilet building clean.Education should also include the proper operation ofthe system, such as what may and may not be disposedof in the toilet, the amount of water to add ifnecessary, and what chemicals should or should not beadded to the system. The user must also be madeaware of what needs to be done if the system fails orwhat options are available when the pit or vault fillsup with sludge.

Current policy is that the basic minimum facility shouldbe a ventilated improved pit (VIP) toilet, or itsequivalent. In this chapter, therefore, levels of servicelower than this will not be discussed.

The use of ponds is frequently considered for dealingwith wastewater in rural areas, and hence theirinclusion in this document.

The five main criteria to be considered when providinga sanitation system for a community are:

reliability; acceptability; appropriateness; affordability; and sustainability.

With these criteria in mind, designers should note thefollowing principles from the White Paper on Basic

1



2GUIDELINES FOR HUMAN SETTLEMENT PLANNING AND DESIGN


Household Sanitation, September 2001:

Sanitation improvement must bedemand-responsive, and supported by anintensive health and hygiene programme

Household sanitation is first and foremost a householdresponsibility and must be demand-responsive.Households must recognise the need for adequatetoilet facilities for them to make informed decisionsabout their sanitation options. For users to benefitmaximally, they must also understand the linkbetween their own health, good hygiene and toiletfacilities.

Community participation

Communities must be fully involved in projects thatrelate to their health and well-being, and also indecisions relating to community facilities, such asschools and clinics. Communities must participate indecision-making about what should be done and how,contribute to the implementation of the decisions, andshare in the benefits of the project or programme. Inparticular, they need to understand the costimplications of each particular sanitation option.

Integrated planning and development

The health, social, and environmental benefits ofimproved sanitation are maximised when sanitation isplanned for and provided in an integrated way withwater supply and other municipal services.

The focal mechanism of achieving integrated planningand development is the municipality-driven IntegratedDevelopment Planning (IDP) process (of which theWater Services Development Plan is a component).

Sanitation is about environment andhealth

Sanitation improvement is more than just theprovision of toilets; it is a process of sustainedenvironment and health improvement. Sanitationimprovement must be accompanied by environmental,health and hygiene promotional activities.

Basic sanitation is a human right

Government has an obligation to create an enablingenvironment through which all South Africans cangain access to basic sanitation services.

The provision of access to sanitationservices is a local governmentresponsibility

Local government has the constitutional responsibilityto provide sanitation services.

Provincial and national government bodies have aconstitutional responsibility to support localgovernment in a spirit of co-operative governance.

Health for all rather than all forsome

The use of scarce public funds must be prioritised, inorder to assist those who are faced with the greatestrisk to health due to inadequate sanitation services.

Equitable regional allocation ofdevelopment resources

The limited national resources available to support theincremental improvement of sanitation services shouldbe equitably distributed throughout the country,according to population, level of development, andthe risk to health of not supporting sanitationimprovement.

Water has an economic value

The way in which sanitation services are provided musttake into account the growing scarcity of good qualitywater in South Africa.

The polluter pays principle

Polluters must pay the cost of cleaning up the impactof their pollution on the environment.

Sanitation services must be financiallysustainable

Sanitation services must be sustainable, in terms ofboth capital and recurrent costs.

Environmental integrity

The environment must be protected from thepotentially negative impacts of sanitation systems.

PLANNING

The various planning stages and other informationrelated to the planning of projects are fully describedin Chapter 9 (Water supply). The planning steps andapproach with respect to sanitation do not differ fromthose described in that chapter, and are not repeatedhere. The reader is thus referred to Chapter 9 forplanning information.

HYGIENE IN SANITATION PROJECTS

An introductory discussion on hygiene in water andsanitation projects can be found in Chapter 9.

For people to change their cultural practices andbehaviours some of which are developed arounddeeply seated values a lot of motivation is required,accompanied by marketing of the new or modifiedpractices. For instance, when people are accustomedto defecating in the open (free of charge) it will takea lot of effort to motivate them to install toilets (at acost), and to use those toilets, which come in as a newpractice. Furthermore, the motivation for installingtoilets or practising a higher level of hygiene mustclearly emphasise the benefits to the individual and tothe community.

The main components of a hygiene-promotion and -education strategy in a project should include thefollowing:

motivation and community mobilisation; communication and community participation; user education (operation and maintenance); skills training and knowledge transfer; development of messages; presentation of messages; and maintenance of good practice.

Many of these components overlap, or cut across thewhole programme of implementation. For instance,motivation and community mobilisation would needto be maintained throughout the programme andafter. The same goes for communication, which isrequired at all stages of a hygiene-promotion and -education programme. In practice there is noparticular cut-off point between one component andanother.

The following should be implemented during theprojects stages (see Appendix A) to ensure that watersupply and sanitation projects have a positive impacton the quality of life and level of hygiene incommunities:

Development and structuring of a strategic plan forthe implementation of hygiene promotion andeducation in water and sanitation projects: Thisstrategic plan should fit in and dovetail withnational and provincial strategies for health andhygiene in South Africa, and should includeadvocacy, training and capacity-building,implementation, monitoring and evaluation.

Liaison with other programmes/projects active inthe health and hygiene field: Other initiativesregarding hygiene (PHAST, etc) should beidentified and coordinated to prevent duplication,and to optimally address the needs of governmentand the communities. A number of other activitiesand programmes in schools, clinics, hospitals andthe media (TV, radio, newspapers, magazines),should be identified and coordinated for a broaderimpact of hygiene promotion and education.

Informing and training local governmentstructures, environmental health officers (EHOs),non-governmental organisations (NGOs),community-based organisations and consultants: Aprogramme should be developed to inform andtrain all local, regional and national institutionsand structures involved in water supply andsanitation, health and hygiene promotion andeducation.

Monitoring and evaluating the implementation ofhygiene in water and sanitation projects: A bodyor organisation should be established and taskedto monitor the quality and standard of hygienepromotion and education. The results of hygienepromotion and education should be evaluatedagainst key health indicators set up at the start ofa project.

Disseminating information regarding hygiene inwater and sanitation projects: The process andresults of hygiene promotion and education in aproject should be disseminated in articles,conference papers, reports, seminars andworkshops with other researchers in the field ofhealth and hygiene.

TECHNICAL INFORMATION

Before a sanitation system is selected, the availableoptions should be examined. This section describes thevarious systems and factors that could influence theselection. Detailed design information is not includedin this chapter. Instead, reference is made to variouspublications in which all the required information maybe found. Some general background information onthe different sanitation technologies is, however,included.

Only sanitation systems commonly used or accepted inSouth Africa are described.

Categories of sanitation systems

There are two ways to handle human waste. It caneither be treated on site before disposal, or removedfrom the site and treated elsewhere. In either case, thewaste may be mixed with water or it may not. On thisbasis the following four groups may be distinguished:

Group 1: No water added requiring conveyance.

Group 2: No water added no conveyance.

Group 3: Water added requiring conveyance.

Group 4: Water added no conveyance.

3





Table 10.1 illustrates the sanitation systems associatedwith each of the above groups. Note that some of thesystems fall somewhere between the four categoriesas, for example, where solids are retained on eachproperty and liquids are conveyed from site, or wherewater may be added, but only in small quantities.Since increasing the number of categories wouldcomplicate the table unnecessarily, these systems havebeen included in the categories that best describe thetreatment of the waste. The operating costs of systemsin which waste is conveyed and treated elsewhere canbe so high that these systems may in the long term bethe most expensive of all. The capital and installationcosts of any conveyance network using largequantities of clean water to convey small quantities ofwaste are very high, and a possibly inappropriatelyhigh level of training and expertise is also required toconstruct and maintain such systems.

Developers should consider all the sanitationalternatives available before deciding on the mostappropriate solution for the community in question. Asolution that may be appropriate in one communitymay be a total failure in another because of cost,customs and religious beliefs, or other factors. Asolution must also not be seen as correct purelybecause developers and authorities have traditionallyimplemented it.

Description of sanitation systems

The main types of sanitation systems are describedbelow. The list is not complete and many commercialmanufacturers provide systems that may be a variantof one or more.

The advantages and disadvantages of each system willdepend on its particular application. What may be adisadvantage in one situation may in fact be anadvantage in another. Thus the advantages and

disadvantages listed after each description should beseen not as absolutes, but merely as aids to selectingthe right sanitation system for a particular application.

Group 1: No water added requiringconveyance(for treatment at a central treatment works)

Chemical toilets (not a preferred option)A chemical toilet stores excreta in a holding tankthat contains a chemical mixture to prevent odourscaused by bacterial action. The contents of theholding tank must be emptied periodically andconveyed to a sewage works for treatment anddisposal. Some units have a flushing mechanismusing some of the liquid in the holding tank torinse the bowl after use. The chemical mixtureusually contains a powerful perfume as well as ablue dye. Chemical toilets can range in size fromthe very small portable units used by campers tothe larger units supplied with a hut. The system canprovide an instant solution and is particularlyuseful for sports events, construction sites or othertemporary applications where the users areaccustomed to the level of service provided by awaterborne sanitation system. The system can alsobe used where emergency sanitation for refugees isrequired, in which case it can give the planners thenecessary breathing space to decide on the bestpermanent solution. It should not be considered asa permanent sanitation option.

Factors to consider before choosing this option arethe following:

Chemical toilets have relatively high capital andmaintenance costs.

It is necessary to add the correct quantity ofchemicals to the holding tank.

Table 10.1: Categories of sanitation systems

REQUIRING CONVEYANCE NO CONVEYANCE REQUIRED(off-site treatment) (treatment, or partial treatment, on site;

accumulated sludge also requires periodic removal)

NO WATER GROUP 1 GROUP 2ADDED Chemical toilet (temporary use only). Ventilated improved pit toilet.

Ventilated improved double-pit toilet.Ventilated vault toilet.Urine-diversion toilet.

WATER GROUP 3 GROUP 4ADDED Full waterborne sanitation. Flushing toilet with septic tank and subsurface soil

absorption field.

Flushing toilet with conservancy tank. Low-flow on-site sanitation systems (LOFLOs):Shallow sewers. Aqua-privy toilet.

Periodic emptying of the holding tank isessential; this requires vacuum tankers, so accessshould be possible at all times.

The system only disposes of human excreta andcannot be used to dispose of other liquid waste.

The units can be installed very quickly andeasily.

They can be moved from site to site.

They require no water connection and requirevery little water for operation.

They are hygienic and free from flies and odour,provided that they are operated andmaintained correctly.

The chemicals could have a negative effect onthe performance of wastewater treatmentworks.

Group 2: No water added no conveyance(treatment or partial treatment on site beforedisposal)

Ventilated improved pit (VIP) toiletThe VIP toilet is a pit toilet with an externalventilation pipe. It is both hygienic and relativelyinexpensive, provided that it is properly designed,constructed, used and maintained. Detailedinformation on VIP design is available in thepublication Building VIPs by Bester and Austin(1997), which is obtainable from the Department ofWater Affairs & Forestry, Pretoria. Information ondifferent soil conditions, as they affect the buildingof VIP toilets, is also included. A SABS Code ofPractice for the construction of VIPs is currentlyunder preparation by the SABS. There are alsovariations of VIP toilets available the Archloo,

Phungalutho, Sanplat, etc. Those mentioned havebeen used with success and are firmly establishedin the industry.

It is possible to construct the entire toilet from localmaterials, although it is more usual to usecommercial products for the vent pipe and thepedestal. Several toilet superstructures are alsocommercially available. When the pit is full, thesuperstructure, pedestal, vent pipe and slab arenormally moved to a freshly dug pit and the old pitis covered with soil. The VIP toilet can be mademore permanent by lining the pit with open-jointed brickwork or other porous lining. The pitcan then be emptied when required, using asuitable vacuum tanker, without the danger of thesides of the pit collapsing. Water (sullage) pouredinto the pit may increase the fill-up rate(depending on soil conditions) and should beavoided; this sanitation technology is therefore notrecommended where a water supply is available onthe site itself.

Factors to consider before choosing this option:

If the stand is small there may be insufficientspace to allow continual relocation of the toilet;therefore arrangements should exist foremptying the toilet.

Unlined pit walls may collapse.

The excreta are visible to the user.

The system may be unable to drain all the liquidwaste if large quantities of wastewater arepoured into the pit.

The cost of the toilet is relatively low; itprovides one of the cheapest forms ofsanitation while maintaining acceptable healthstandards.

The toilet can be constructed by the recipients,even if they are unskilled, as very little trainingis required.

Locally available materials can be used.

If required, the components can bemanufactured commercially and erected on alarge number of plots within a short space oftime.

The system is hygienic, provided that it is usedand maintained correctly.

The system can be used in high-density areasonly if a pit-emptying service exists.

5



Figure 10.1: Chemical toilet unit



The system can be upgraded at a later stage toincrease user convenience (e.g. to a urine-diversion toilet).

The system cannot ordinarily be installed insidea house.

The quantity of water supplied to the siteshould be limited.

If a pit-emptying service exists, proper access tothe pit should be provided.

Ventilated improved double-pit (VIDP) toiletThe VIDP toilet, also known as the twin-pitcomposting toilet, was developed mainly for use inurban areas where, because of limited space on thesmaller plots, it may be impossible to relocate thetoilet every time the pit becomes full. The VIDP is arelatively low-cost and simple but permanentsanitation solution for high-density areas. Twolined shallow pits, designed to be emptied, areexcavated side by side and are straddled by a singlepermanent superstructure. The pits are usedalternately: when the first pit is full it is closed andthe prefabricated pedestal is placed over thesecond pit. After a period of at least one year theclosed pit can be emptied, either manually (if this isculturally acceptable) or mechanically, and then itbecomes available for re-use when the other pit isfull. Each pit should be sized to last a family two tothree years before filling up. It is important thatthe dividing wall between the pits be sealed, toprevent liquids seeping from the pit currently inuse into the closed pit, thus contaminating it. TheVIDP toilet can be built partially above the groundin areas where there is a high water table, but thedistance between the pit floor and the highestwater table should be at least 1 m.

Detailed information on VIDP design is alsoavailable in the publication Building VIPs by Besterand Austin (1997), obtainable from theDepartment of Water Affairs & Forestry, Pretoria.

Factors to consider before choosing this option aresimilar to those for the VIP, but include thefollowing:

Some training is required to ensure that the pitlining is properly constructed.

The contents of the used pit may be safely usedas compost after a period of about two years inthe closed pit.

The user may not be prepared to empty the pit,even though the contents have composted.

The superstructure can be a permanentinstallation.

The system can be regarded as a permanentsanitation solution.

The system can be used in high-density areas.

The system can be used in areas with hardground, where digging a deep pit is impractical.

Ventilated vault (VV) toiletsThe VV toilet is basically a VIP toilet with awatertight pit that prevents seepage. It can beregarded as a low-cost, permanent sanitationsolution, especially in areas with a highgroundwater table or a poor capacity for soilinfiltration, or where the consequences of possiblegroundwater pollution are unacceptable.

Figure 10.3: VIDP toilet

Figure 10.2: VIP toilet

The amount of wastewater disposed of into thevault should be limited to avoid the need forfrequent emptying, so it is advisable not to use thistype of sanitation technology where a water supplyis available on site. Should an individual waterconnection be provided to each stand at a laterdate, as part of an upgrading scheme for theresidential area, then the vault can be utilised as asolids-retention tank (digester) and liquids can bedrained from the site using a settled-sewagesystem, also called a solids-free sewer system (seethe section on settled-sewage systems underGroup 3). Ventilation, odour and insect controloperate on the same basis as the VIP toilet.

Factors to consider before choosing this option aresimilar to those of the VIP, but include thefollowing:

It is necessary to make use of a vacuum-tankerservice for periodic emptying of the vaults.

Builder training and special materials arerequired if a completely waterproof vault isrequired.

The system can be used in areas with a highwater table if the vault is properly constructed.

The system can be used in areas where pollutionof the groundwater is likely if a VIP toiletsystem is used.


This system provides very good opportunitiesfor upgrading since the vault can be used as asolids-retention tank when upgrading to solids-free sewers.

The cost of emptying equipment and theoperation of a vacuum-tanker service could beexcessive (see also the section on vacuumtankers).

Urine-diversion (UD) toiletThe urine-diversion toilet, also known as the dry-box, is a superior type of dry toilet thatcircumvents the problems sometimes encounteredwith the implementation of VIP toilets, namelyunfavourable geotechnical or hydrologicalconditions, high-density settlements with smallerven, etc. The main advantage is that a pit is notrequired, so the toilet may be installed inside thehouse, if desired by the owner. Urine is diverted atsource by a specially designed pedestal and, owingto the relatively small volumes involved, may simplybe led into a shallow soakpit. Alternatively, urinecan be easily collected in a container and re-usedfor agricultural fertiliser, as it is rich in plantnutrients such as nitrogen, phosphorus andpotassium. Faeces are deposited in a shallow vaultand covered with a sprinkling of ash or dry soil,which absorbs most of the moisture. They arefurther subjected to a dehydration process insidethe vault, which hastens pathogen die-off.Depending on the temperature and degree ofdesiccation attained in the vault, the faeces may besafe to handle after a period of six to eighteenmonths, and can then be easily removed from thevault and either disposed of or re-used as soilconditioner, depending on individual preferences.

Other favourable aspects of this type of toilet arean absence of odours or flies (if it is properly used),a relatively low capital cost that may, depending onthe specific circumstances, be even less than a VIPtoilet, and a negligible operating cost. There arealso environmental advantages, due to the factthat no pit is required.

Detailed guidelines on the implementation of thistechnology are contained in the publication Urine-diversion ecological sanitation systems in SouthAfrica by Austin and Duncker (CSIR, 2002).

Factors to consider before choosing this option:

The technology is well suited to dense urbansettlements and places where environmentalconditions do not favour other types ofsanitation.

Use of the toilet requires an adherence tocertain operational requirements, and a propercommitment from owners is required. Gooduser education is therefore especiallyimportant.

Building materials similar to those for a VIPtoilet may be used, and the toilets can be

7



Figure 10.4: Ventilated vault toilet



constructed by relatively unskilled persons.Components can also be manufacturedcommercially.

The system is hygienic, provided that it is usedand maintained correctly. Safe re-use of theurine and faeces is also facilitated.

The system can be installed inside a house, ifdesired.

There may be reluctance on the part of the userto empty the vault, even though the contentsare innocuous.

The system can be regarded as a permanentsanitation solution that will never needupgrading.

Group 3: Water added requiring conveyance(treatment at a central works)

Full waterborne sanitationThis is an expensive option and requires ongoingmaintenance of the toilet installation, the sewerreticulation and the treatment works, and therecipient community should be informedaccordingly. The system requires a water supplyconnection to each property. The water is used toflush the excreta from the toilet pan and into thesewer, as well as to maintain a water seal in thepan. The excreta are conveyed by the water, inunderground pipes, to a treatment works that maybe a considerable distance from the source. Thetreatment works must be able to handle the highvolume of liquid required to convey the excreta.The quantity of water required (usually 6-10 litresper flush) can be reduced by using low-flush pansdesigned to flush efficiently with as little as three

litres. Research has indicated that the operation ofthe sewer system is not adversely affected by low-volume flush toilets. Flush volumes of 8-9 litres arenormally used, however. In an area where water iscostly or scarce, it may be counter-productive topurify water only to pollute it by conveying excretato a treatment and disposal facility.


The system is expensive to install, operate andmaintain.

The system can be designed and installed onlyby trained professionals.

The treatment works must be operated andmaintained properly if pollution of waterwaysis to be avoided.

The system requires large amounts of water tooperate effectively and reliably.

The system is hygienic and free of flies andodours, provided that it is properly operatedand maintained.

A high level of user convenience is obtained.

The system should be regarded as a permanentsanitation system.

The toilet can be placed indoors.

This system can be used in high-density areas.

An adequate, uninterrupted supply of watermust be available.Figure 10.5: Urine-diversion toilet

Figure 10.6: Waterborne sewerage system

Shallow sewersThe shallow sewer system is basically aconventional system where a more simpleapproach with respect to design and construction isfollowed. Basically it entails a system wheregradients are flatter, pipes are smaller and laidshallower, manholes are smaller and constructed ofbrickwork, and house connections are simpler.Where such systems are installed, communityinvolvement in management and maintenanceissues is preferred.

Design of sewer networks:

The professional responsibility in design remainswith the engineer, and guidelines should never beregarded as prescriptive. Most local authoritieshave their own requirements and preferences ontechnical detail, such as pipe slopes, manholedetails, materials, and so on. These are based ontheir own particular experiences and new designsshould therefore be discussed with the relevantcontrolling authority.

Designers should not assume that sewer systemswill always be properly maintained, and allowanceshould be made for this.

The hydraulic design of the sewers should be doneaccording to acceptable minimum and maximumvelocities in the pipeline. A number of pipemanufacturers have design charts available in theirproduct manuals and these can be used in theabsence of other guidelines.

The construction of a system should be inaccordance with the relevant sections of SABS1200:1996. The depth of the sewer is normallydetermined by its position on site. Sewers in mid-block positions and on sidewalks can normally belaid at shallower depths. Should laying of sewerand water pipes in the same trench be considered,workmanship should be of a high standard.Appendix C gives design guidelines that should beuseful.

Flushing toilet with conservancy tankThis system consists of a standard flushing toiletthat drains into a storage or conservancy tank onthe property; alternatively, several propertiestoilets can drain into one large tank. A vacuumtanker regularly conveys the excrement to a centralsewage treatment works for purification beforethe treated effluent is discharged into awatercourse. The appropriate volume of theconservancy tank should be calculated on the basisof the planned emptying cycle and the estimatedquantity of wastes generated. Tank volumes aresometimes prescribed by the service provider.


The system is expensive to install, operate andmaintain, although the capital cost is lowerthan the fully reticulated system.

The system can be designed and installed onlyby trained professionals.

A treatment works must be operated andmaintained properly to avoid the pollution ofwaterways.

A fleet of vacuum tankers must be maintainedby the local authority.

Regular collection is essential.

The system is hygienic and free of odours,provided that it is properly operated andmaintained.




9



Figure 10.7: Shallow sewer system Figure 10.8: Flushing toilet with conservancy tank

10



This system has good potential for upgradingsince the conservancy tank can be used as adigester when upgrading to a settled-sewagesystem.

An adequate, uninterrupted supply of watermust be available.

Settled sewage system In settled sewage systems, also known as solids-freesystems or Septic Tank Effluent Drainage (STED),the solid portion of excreta (grit, grease andorganic solids) is retained on site in an interceptortank (septic tank), while the liquid portion of thewaste is drained from the site in a small-diametersewer. Such sewers do not carry solids, and havevery few manholes. Tolerances for excavation andpipe laying may be greater than for conventionalsewers, allowing lesser skilled labour to be used.Although the liquid portion of the waste must betreated in a sewage works, the biological designcapacity of the works can be greatly reducedbecause partial treatment of the sewage will takeplace in the retention tank on the site. The tankwill also result in a much lower peak factor in thedesign of both the reticulation and the treatmentworks. The retention tank should be inspectedregularly and emptied periodically, to preventsludge overflowing from the tank and entering thesewer. This system is an easy upgrading route fromseptic tanks with soakaways, conservancy tanks,and other on-site systems, as they can be connectedto a settled-sewage system with very littlemodification. Tipping-tray pedestals and water-saving devices can also be used in settled-sewageschemes without fear of causing blockage resultingfrom the reduced quantity of water flowing in thesewers.


The system requires a fairly large capital outlayif new interceptor tanks have to be constructed(i.e. if there are no existing septic tanks whichcan be used).

Care must be taken to ensure that only liquidwaste enters the sewers; this may mean regularinspection of the on-site retention tanks.

Vacuum tankers must be maintained by thelocal authority.

The system is hygienic and free of flies andodours, provided that it is properly operatedand maintained.


The system can be regarded as a permanentsanitation system.


All household liquid waste can be disposed ofvia this sanitation system.

The sewers can be installed at flatter gradientsand can even be designed to flow underpressure.

The system provides an easy and reasonablypriced option when areas with on-sitesanitation need to be upgraded, because ofincreased water consumption and higher livingstandards.


An adequate uninterrupted supply of watermust be available.

Regular inspection of the septic tank/digester isrequired to prevent an overflow of sludge.

Technical information on the design of thesesystems may be found in the CSIR, Division ofBuilding and Construction Technology publicationSeptic tank effluent drainage systems (1997).

Group 4: Water added no conveyance(treatment or partial treatment on site beforedisposal)

These systems generally dispose of all or part of theeffluent on site. Some systems retain only the solidportion of the waste on site and the liquids areconveyed to a suitable treatment and disposal facility.

Figure 10.9: Settled sewage system

Systems that dispose of the liquid fraction on siterequire a soil percolation system, and the amount ofliquid that can be disposed of will depend on thesystems design and the permeability of the soil.

Flushing toilet with septic tank and soakawayWater is used to flush the waste from aconventional toilet pan into an underground septictank, which can be placed a considerable distancefrom the toilet. The septic tank receives the sewage(toilet water and sullage (greywater)) and thesolids digest and settle to the bottom of the tank inthe same manner as in the settled-sewage system.The septic tank therefore provides for storage ofsludge. The effluent from the tank can containpathogenic organisms and must therefore bedrained on the site in a subsoil drainage system.The scum and the sludge must be prevented fromleaving the septic tank as they could causepermanent damage to the percolation system. It istherefore advisable to inspect the tank at intervalsto ascertain the scum and sludge levels. Most tankscan be emptied by a conventional vacuum tanker.Liquid waste from the kitchen and bathroom canalso be drained to the septic tank. Septic tanksshould be regarded as providing a high level ofservice.


It is relatively expensive and requires a waterconnection on each stand.

It requires regular inspection, and sludgeremoval every few years, depending on thedesign capacity of the septic tank.

Percolation systems may not be suitable in areasof low soil permeability or high residentialdensity.

It provides a level of service virtually equivalentto waterborne sanitation.

The system is hygienic and free of flies.

The toilet can be inside the dwelling.

This system has excellent potential forupgrading, since the septic tank outlet caneasily be connected to a settled-sewage systemat a future date.


Designers are referred to the publication Septictank systems (BOU/R9603), available from the CSIR,Division of Building and Construction Technology,for information on the design of septic tanks.

Reference to the percolation capacity of soils ismade later in this chapter under the sectionEvaluation of sites.

Low-flow on-site sanitation systems ( LOFLOs)The term LOFLOs refers to the group of on-sitesanitation systems that use low volumes of waterfor flushing (less than 2,5 litres per flush). Thesesystems include a pedestal, digestion capacity andsoakaway component. They are:

aqua-privies; pour-flush toilets* and low-flush systems*; and low-flow septic tanks*.

*These types are not generally found in SouthAfrica.

Aqua-privies:

An aqua-privy is a small, single-compartment septictank directly under or slightly offset from thepedestal. The excreta drops directly into the tankthrough a chute, which extends 100 mm to 150 mmbelow the surface of the water in the tank. Thisprovides a water seal, which must be maintained atall times to prevent odour and keep insects away.The tank must be completely watertight; it maytherefore be practical to use a prefabricated tank.The tank must be topped up from time to time withwater to compensate for evaporation losses ifflushing water is not available. This can be done bymounting a wash trough on the outside wall of thesuperstructure and draining the used water into thetank. The overflow from the tank may containpathogenic organisms and should therefore run intoa soil percolation system (it can also be connected toa settled-sewage system at a later stage).

11



Figure 10.10: Flushing toilet with septic tank andsoakaway

12




The excreta are visible to the user.

The tanks must be completely watertight.

The user must top up the water level in theaqua-privy to compensate for evaporationlosses.

The system is hygienic, provided that it is usedand maintained correctly.

It is relatively inexpensive.

The system can be regarded as a permanentsanitation solution.

This system has excellent potential forupgrading, since the tanks work in the sameway as a septic tank and can thus be connecteddirectly to a settled-sewage system.

The tanks need regular inspection, and sludgeremoval is required from time to time.


FACTORS AFFECTING THE CHOICE OFA SANITATION SYSTEM

General considerations

The primary reason for installing a sanitation system ina community is to assist in the maintenance of healthand should be seen as only one aspect of a total healthprogramme. The choice of a sanitation system by acommunity will be influenced by several factors, suchas the following:

The system should not be beyond the technologicalability of the community insofar as operation andmaintenance are concerned.

The system should not be beyond the communitysability to meet the capital as well as themaintenance costs.

The system should take into account the level ofwater supply provided, and possible problems withsullage (greywater) management.

The likelihood of future upgrading should beconsidered, particularly the level of service of thewater-supply system.

The system should operate well despite misuse byinexperienced users.

In a developing area the system should require aslittle maintenance as possible.

The system chosen should take into account thetraining that can be given to the community, froman operating and maintenance point of view.

The system should be appropriate for the soilconditions.

The community should be involved to the fullestextent possible in the choice of an appropriatesystem.

To foster a spirit of real involvement andownership, the community should be trained to doas much as possible of the development workthemselves.

Local customs should be carefully considered.

The local authority should have the institutionalstructure necessary for the operation andmaintenance of the system.

The existing housing layout, if there is one, shouldnot make the chosen system difficult to construct,maintain or operate.

Figure10.11: Aqua-privy toilet

Environmental factors should be considered:surface pollution, possible groundwatercontamination, etc.

The cost of the system

Many people in developing areas are not only unableto afford sophisticated sanitation systems, but thesesystems may also be technically inappropriate forthem. At the same time, the sanitation alternativewith the lowest overall cost may also be inappropriatebecause of the communitys cultural background orbecause of its unwillingness or inability to operate thesystem correctly.

When the costs of different systems are compared, allrelevant factors should be taken into account.Examples of costs often ignored are the following:

A pit toilet may require relocation on the site oremptying every 4-10 years, depending on itscapacity.

Sludge from septic tanks and other on-sitesanitation systems may require treatment beforedisposal.

Training may be required for operators andmaintenance staff.

The community may have to be trained in the useof the system for it to operate effectively.

Regional installations such as treatment works maybe required.

Special vehicles and equipment may be requiredfor operation or maintenance.

To keep costs to a minimum, several issues arerelevant:

Who pays what? For example, if a governmentinstitution or development agency is paying all ofthe capital costs, then the community will generallydemand the most expensive, highest level ofsanitation. If, on the other hand, the capital costsare to be recovered from the community, then itschoice of sanitation system may be quite different.The lack of income to pay for maintenance couldhave serious financial implications as well as healthrisks.

Would the community prefer lower capital costsand higher maintenance costs, or vice versa?

Will the cost comparison between options changeif all the potential benefits and costs are included?

Are any of the costs incorrectly or dishonestlyrepresented? For example, have capital grants or

soft loans been ignored? Do certain services havehidden subsidies that produce misleadingcomparisons (for example, where treatment costsare paid by regional authorities)?

Where finance is limited, developers should consultthe community, determine its priorities, and seek waysto achieve the improvements desired. This may takeextra time but a motivated community will contributemore to successful project implementation and,perhaps more importantly, to the long-term operationand maintenance of the system selected.

Sanitation at public facilities

Sanitation facilities are required at public buildingssuch as schools and clinics. The large number of peopleusing a concentrated facility can cause problems ifthere is inadequate on-site drainage and a lack ofgeneral maintenance, such as cleaning of the toiletand replacement of toilet paper. Most types of on-sitesanitation systems can be used, provided thatdevelopers take note of the special requirements forpublic facilities.

Generally speaking, the system should use as littlewater and require as little routine maintenance aspossible. Before choosing a system that requires dailymaintenance for effective operation, one must ensurethat maintenance tasks will in fact be performed. Arural school may not be able to afford the services of ajanitor to look after routine maintenance.

The number of sanitation units required at schools iscovered in the National Building Regulations (SABS0400:1990). Because of the number of users, careshould be taken to prevent pollution of thegroundwater, particularly if there is a boreholesupplying the school with water.

Urinals that do not require water for flushing areavailable from commercial sources. These can be usedeffectively in sanitation facilities. However, theyrequire the weekly addition of a special oil to the trapand the application of a special deodorised cleanser tothe bowl or slab. They perform satisfactorily as long asthe weekly maintenance is carried out and shouldtherefore be used only where the necessary trainingcan be given to the cleaners and where the supply ofoil and cleanser can be assured.

DISPOSAL OF SLUDGE FROM ON-SITESANITATION SYSTEMS

All forms of on-site sanitation will result in anaccumulation of sludge that, at intervals, must beremoved from the pit or tank and conveyed to sometreatment or disposal facility. If the pit or tank containsfresh sewage, the sludge must be treated or disposedof in a way that will not be harmful to the

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environment or a threat to health; if the waste matterhas been allowed to decompose to the extent wherethere are no longer any pathogens present, the sludgecan be spread on the land as compost.

Sludge can be disposed of only in accordance with theprescribed methods. See Water Research Commission(1997) Permissable utilisation and disposal of sewagesludge.

An effective refuse-collection system should be inoperation in high-density residential areas and peopleshould be encouraged to use it. If this is not done, theresidents will probably use the toilet to dispose of tins,bottles, plastic and other forms of refuse which willresult in the pits filling very rapidly. This will presentproblems when emptying pits with a vacuum tanker.Where regular emptying will be required, it isadvisable to construct permanent pits with lined wallsto prevent damage during emptying, which could leadto the collapse of the pit walls. Note, however, that pitlinings should make allowance for percolation ofeffluent into the surrounding soil (e.g. by leaving thevertical joints of a brick lining unfilled). A regularprogramme for pit emptying in an area is better thanresponding to individual ad hoc calls for pit emptying.

Composition of pit or vault contents

In a sealed tank or vault, human excreta will usuallyseparate into three distinct layers, namely a layer offloating scum, a liquid layer and a layer of sediment.Well-drained pits may have no distinct liquid layer, andtherefore no floating scum layer. The scum layer seemsto be caused by the presence of paper, oil and greasein the tank and it is also more prominent in tanks witha large number of users. It is usually possible to breakup the scum layer without much effort. The watercontent of pits can vary between 50% and 97%,depending on the type of sanitation system, thepersonal habits of the users, the permeability of thesoil, and the height of the groundwater table.Cognisance should be taken of the fact that differentmaterials used for anal cleansing will have differentbreakdown periods. Newspaper will require more timeto break down than ordinary toilet paper, and in somecases will not break down at all. This will obviouslycause the pit to fill up more quickly.

Methods of emptying pits

It is possible to empty pits manually, using scoops andbuckets, and to dig out the thicker sludge with spades,but this poses obvious health risks to the workersinvolved. The use of ventilated improved double-pittoilets overcomes this unpleasantness by allowing theexcreta to decompose into a pathogen-free, humus-rich soil, after storage in the sealed pit for about twoyears. However, many people do not like to emptytheir pits manually.

The most suitable method of emptying a pitmechanically involves the use of a vacuum tanker,where a partial vacuum is created inside a tank andatmospheric pressure is used to force the pit contentsalong a hose and into the tank. The use of a vacuum ispreferred to other pumping methods, because thecontents do not come into contact with the movingparts of the pump, where they can cause damage orblockages. Various techniques can be used to conveythis sludge along the pipe to the tank. Thin sludgewith a low viscosity can be conveyed by immersing thenozzle below the surface of the sludge, drawing aconstant flow into the tank.

Thicker, more viscous sludge requires a pneumaticconveying technique, where the particles of wastematter are entrained in an air stream. This can beachieved by holding the end of the nozzle a fewcentimetres above the surface of the waste and relyingon the high velocity of the air to entrain particles andconvey them along the pipe to the holding tank. Thistechnique requires very high-capacity air pumps tooperate effectively. Devices such as an air-bleed nozzlecan be used to obtain the same effect with lessoperator skill and smaller air pumps. Pneumaticconveyance can also be achieved with a low-capacityair pump by using the plug-drag (or suck-and-gulp)technique. This method relies on submerging the hoseinlet, allowing a vacuum pump to create a vacuuminside the tank, then drawing the hose out to allow ahigh-velocity air stream to convey a plug of waste intothe tank. The plug-drag technique works best with avehicle with a fairly high-capacity pump (say 10 m3/min) and a relatively small holding tank(1,5-2 m3).

Sludge flow properties

Sludge generally exhibits a yield stress, shear thinningbehaviour and thixotropy. In effect, this means thatthe hardest part of the operation is to get the sludgemoving. The addition of small quantities of water tothe sludge can assist greatly in getting it to move bycausing shearing to take place. Being thixotropic, thesludge remembers this and exhibits a lower shearingstress next time.

Vacuum tankers

Most vacuum tankers available today are designed foruse in developed countries, where roads are good andmaintenance is properly done. However, somemanufacturers are realising the special conditions thatexist in developing countries and are now adaptingtheir designs or, even better, are developingcompletely new vehicles designed to cope with theactual conditions under which these vehicles will haveto work.

The size of conventional vacuum tanker vehiclesprevents their gaining easy access to toilets. They are

high off the ground, which may limit the depth of pitthat can be emptied, and they are so heavy whenloaded that travelling over bad or non-existent roadsis extremely difficult. The equipment on the vehicle isoften complex and requires regular maintenance,which is seldom carried out by the unskilled peoplewho, in most cases, will operate the vehicles. Waterysludge from conservancy tanks and septic tanks maynot be a problem, but the tankers often cannot copewith the more viscous sludge found in pit toilets.

A purpose-designed pit-toilet-emptying vehicle shouldhave the following attributes:

a low mass;

a low overall height;

high manoeuvrability;

ability to travel on extremely poor roads;

a small-capacity holding tank with a relatively high-capacity pump, to facilitate the use of plug-dragtechniques;

the ability to transfer its load to another vehicle ortrailer if there are long haul distances to thedisposal site;

both vehicle and equipment must be robust;

little skill should be required to operate the vehicleand the equipment;

capital and operating costs must be as low aspossible, to facilitate operation by emergingcontractors or entrepreneurs;

a small pressure pump and water for washingdown must be provided; and

storage compartments must be provided for thecrews personal effects.

Disposal of sludge

Pit-toilet sludge can be disposed of by burial intrenches.

Dehydrated faecal matter from urine-diversion toiletsmay be safely re-used as soil conditioner, or,alternatively, disposed of by burial, if preferred. It mayalso be co-composted with other organic waste.

Sludge from septic tanks, aqua-privies, etc, can bedisposed of only in accordance with the prescribedmethods. See Water Research Commission (1997)Permissable utilisation and disposal of sewage sludge.

Unless the sludge has been allowed to decomposeuntil no more pathogens are present, it may pose athreat to the environment, particularly where theemptying of pits is practised on a large scale. Thedesign of facilities for the disposal of sludge needscareful consideration, as the area is subject tocontinuous wet conditions and heavy vehicle loads.The type of equipment employed in the disposal effortshould be known to the designer, as discharge speedand sludge volume need to be taken into account.Cognisance should be taken of the immediateenvironment, as accidental discharge errors may causeserious pollution and health hazards.

Emptying facilities at treatment works need not beelaborate, and could consist of an apron on which todischarge the contents of the vehicle and a wash-downfacility. The nature of the sludge can vary widely andthis should be taken into account when designing thesewage works. Depending on the habits of the pitowners and the effectiveness of refuse removal in thearea, there may also be a high proportion of rags,bottles and other garbage in the sludge. Generally ahigher grit load will also come from developingcommunities. Pond systems can be very effective intreating sludge from on-site sanitation systems. If theponds treat only sludge from pit latrines it may benecessary to add water to prevent the ponds fromdrying out before digestion has taken place. Sludgefrom on-site sanitation systems can also be treated bycomposting at a central works, using forced aeration.

Although it is usually still necessary to treat sludgefrom on-site sanitation systems, the cost of treatmentis lower than for fully waterborne sanitation. This isbecause partial treatment has already taken place onthe site through the biological decomposition of thewaste in the pit or tank. In addition, the treatmentworks do not have to be designed to handle the largequantities of water which must be added to the wastefor the sole purpose of conveying solids along anetwork of sewer pipes to the treatment and disposalworks.

EVALUATION OF SITES

It is not possible to lay down rigid criteria for thesuitability of a site for on-site sanitation, because soiland site conditions vary widely. Two basic criteriashould, however, be considered namely, whether thesoil can effectively drain the liquids brought to the siteand whether there is any danger of pollution of thegroundwater or surface water.

Topographical evaluation

All features that can affect the functioning of thesanitation system should be noted and marked on thesite plans during a visual survey of the site. Theposition of depressions, gullies, rock outcrops and

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other features should be noted and an assessmentmade of how they are likely to affect the functioningof the system. The type and gradient of slopes shouldalso be noted as steep slopes can result in the surfacingof improperly treated effluent, especially duringperiods of high rainfall. Surface and subsurfacedrainage patterns, as well as obvious flood hazards,should be reported. The vegetation on the site willoften reflect soil-drainage characteristics.

Soil profiles

Sampling holes should be excavated to a depth of atleast one metre below the bottom of proposed pittoilets or soakaways. Soil properties (such as texture,structure and type) should be determined. Thepresence of bedrock, gravel, groundwater or a layerwith poor permeability should be noted. Soil mottlingindicates the presence of a high seasonal groundwatertable, which can affect soil percolation.

Percolation capacity of the site

If the soil is unable to drain liquid waste effectively,swampy, unsanitary conditions can result. This canoccur in areas with very shallow water tables or withpoor permeability, or where a shallow, restrictive layersuch as bedrock occurs. On-site sanitation can be usedin low-permeability soils, but the system must becarefully selected in relation to the quantity of watersupplied to the site. If the efficient functioning of asoil-percolation system is in doubt, it is advisable tocreate an inspection point where the level of thewater in the subsoil drain can be monitored, so thatadequate warning of failure is obtained to allow thelocal authority to plan for an alternative solution toliquid drainage problems before a crisis develops. Thiswill be effective only if the recipient community fullyunderstands the need for regular inspection of thedrain, as well as the consequences of failure. On-sitesanitation can be used in areas with poor percolation,but it may be necessary to retain all the liquids on thesite in a sealed vault and provide a regular emptyingservice, or to drain the site with settled sewagesystems.

The percolation test is designed to quantify themovement of liquids in the soil at a specific time of theyear. Percolation rates usually change as the soilsmoisture content changes, and it is best to conduct thetest in the rainy season. The percolation test should beregarded only as an indication of the suitability of thesoil for a specific sanitation system. The followingprocedures should be complied with:

Calculation of number of test holes

The number of test holes needed is determined by thesize of the settlement and the variability of the soilconditions. Usually test holes should be spaceduniformly throughout the area, at the rate of five to

ten holes per hectare, if soil conditions are fairlyhomogeneous.

Percolation test

The test procedure to be followed is described in SABS0400.

POLLUTION CAUSED BY SANITATION

When there is a high density of people living in anarea, both the surface water and groundwater can beexpected to become polluted to some degree,irrespective of the type of sanitation system used inthe area. Some basic precautions will minimise the riskof serious pollution.

Surface pollution

The surfacing of partially treated effluent can create adirect health risk, and can cause pollution of surfacewaters. This type of pollution should and can usuallybe avoided. It is most likely to occur in areas where thegroundwater table is very high or in areas with steepslopes where a shallow, permeable layer of topsoilcovers an impermeable subsoil. In areas where cut-and-fill techniques are used to provide platforms forhouse construction, sanitation units and soakawaysshould be carefully sited to minimise the possibility ofsurface pollution. Sanitation units and soakawaysshould also be sited in such a way that rainwateringress cannot occur, as this could cause flooding, withresultant surface pollution.

Poor maintenance of reticulation systems, pumpingstations and sewage-purification works can causeserious pollution with associated health risks,especially in remote areas close to streams and rivers.

Groundwater pollution

Groundwater can be contaminated by a sanitationsystem; therefore the risk should be assessed or thegroundwater periodically monitored, particularlywhere this water is intended for human consumption.The guidelines made available in the publication Aprotocol to manage the potential of groundwatercontamination from on-site sanitation by theDirectorate of Geohydrology of the Department ofWater Affairs & Forestry (1997), should be observed.The soil around the pit toilet or subsurface drainprovides a natural purification zone, and tests carriedout both in South Africa and other parts of Africaindicate that on-site sanitation does not pose a seriousthreat, provided the water is not intended for humanconsumption. Generally, the susceptibility of a watersource to pollution decreases quite sharply withincreasing distance and depth from the source ofpollution, except in areas with fissured rock, limestone,very coarse soil or other highly permeable soils.

Soakaways attached to on-site sanitation systemsshould, wherever possible, be located downstream ofdrinking water supplies. The following could be usedas a guide for the location of a soakaway:

7,5 m from the drinking-water source if the highestseasonal water table is more than 5 m below thebottom surface of the pit or soakaway;

15 m from the water source if the highest seasonalwater table is 1-5 m below the bottom surface ofthe pit or soakaway;

30 m from the water source if the highest seasonalwater table is less than 1 m below the bottom ofthe pit or soakaway; and

there is no safe distance from a source of drinkingwater in areas that have fissured rock, limestone orvery coarse soil.

These distances are given as a guide only. Permeabilityof the soil is not the only factor. Geology, topography,the presence of trees, groundwater flow direction, etc,also influence the position of the borehole (Xu andBraune 1995).

SULLAGE (GREYWATER) DISPOSAL

General

On-site excreta-disposal technologies require thatseparate provision be made for the disposal of sullage.Sullage, also referred to as greywater, is defined as alldomestic wastewater other than toilet water. Thisrefers to wastewater from baths, sinks, laundry andkitchen waste. Although this greywater is supposednot to contain harmful excreted pathogens, it oftendoes: washing babies nappies, for example,automatically contaminates the water. Sullage,however, contains considerably fewer pathogenicmicro-organisms and has a lower nitrate content thanraw sewage. It also has a more soluble andbiodegradable organic content.

Sullage is produced not only on private residentialstands but also at communal washing places and taxistands, and provision should therefore be made for itsdisposal.

Volumes

The per capita volume of sullage generated dependson the water consumption. The water consumption isto a large extent dependent on the level of watersupply and the type of on-site sanitation thecontributor enjoys. It is not difficult to find localfigures of generation and one should try to obtainthese, even if it requires actual measurement in thefield. Typical figures are given in Table 10.2.

Health aspects

Mosquito breeding can take place where ponds arecreated by casual tipping of sullage, and conditionsfavourable for the development of parasitic wormscould also be created in this way. Infection can alsooccur in constant muddy conditions. In order to reducepotential health hazards, it is of the utmostimportance to choose the right option for sullagedisposal. See also Figure 6.31, Chapter 6.

Disposal

The type of disposal system chosen by the designer willdepend on various factors such as the availability ofland, the volume of sullage generated per day, the riskof groundwater pollution, the availability of opendrains, the possibilities of ponding and thepermeability of the soil. Where water is available onthe site, a disposal facility should definitely beconsidered.

Disposal systems

Sullage can be used to effect flushing of certainsystems.

Casual tipping

Casual tipping in the yard can be tolerated, providedthe soil has good permeability and is not continuallymoist. Where casual tipping takes place under otherconditions it may result in ponding and/or muddyconditions, with adverse health effects as mentionedabove. Good soil drainage and a low populationdensity can accommodate this practice.

Garden watering

This practice can also be tolerated, provided plants andvegetables that are watered in this manner are noteaten raw, for disease transmission may occur.

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Standpipes, water vendors. Pit toilets. 20 - 30

On-site single-tap supply (yard connection). Pit toilets. 30 - 60

Table 10.2: Sullage generation

AVAILABLE WATER SUPPLY AND SANITATION SULLAGE GENERATION LITRES PER CAPITA PER DAY

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Soakaways

A soakaway is probably the safest and mostconvenient way of disposing of sullage, as long as soilconditions permit this. The design of the soakaway canbe done according to the guidelines given in SABS0400. Designers should be aware that groundwaterpollution is still a possibility, though to a much lesserextent. Where simple maintenance tasks are able to becarried out, the use of grease traps should beconsidered.

Piped systems

The disposal of sullage in piped systems is hardly everan economical solution, although it may be a viableoption when dealing with communal washing pointsgenerating large amounts of sullage. Solids-free sewersystems are ideal for this purpose.

Sullage treatment

The fairly high BOD5 value of sullage (typically 100mg/l) makes it unsuitable for discharging into riversand streams. If treatment is required, single facultativeponds could be used.

TOILET PEDESTALS AND SQUATTINGPLATES

Various types of toilet pedestals and squatting platescan be used with on-site sanitation systems. Membersof some cultures are used to squatting for defecation,and cases of constipation have been recorded whenthey change to a sitting position. Some cultures alsorequire water for anal cleansing.

The simplest form of appliance is a plain seat orpedestal, or a squatting plate. The hole should beapproximately 250 mm in diameter for adults, andhave a cover to restrict the access of flies and otherinsects to the pit. It is good practice to provide asecond seat with a hole size of approximately 150 mmfor young children, so that they need not fear fallinginto the pit. The plain seat found in a VIP toiletnormally has similar dimensions.

Pedestals with water seals can be used in conjunctionwith most sanitation systems. Various methods can beemployed to effect a water seal in a toilet system. Theysignificantly increase user convenience by eliminatingodour and screening the contents of the pit. Somewater seal appliances require a piped water supply.These are not recommended for on-site sanitationsystems, unless the extra water can be disposed of onthe site (see the section on sullage disposal). Mostwater seal appliances can operate efficiently on a tankfilled by a bucket of household wastewater.

A conventional toilet bowl is an example of a water

seal pedestal, but it can require between 6 and 12litres per flush. Special pans or bowls, so-called low-volume flush pans, have been developed that requireonly three litres per flush. These low-volume flushtoilets do not have any negative effects on the self-cleaning capacity of waterborne sewerage systems.Various tipping-tray designs are also available, withflush requirements varying from 0,75 to 2 litres,depending on the design. These appliances have ashallow pan or tray that holds the water necessary forthe seal. After use the tray is cleared by tipping it,allowing the waste matter to fall into the pit below.Thus the water is used solely for maintaining the seal,not for clearing the pan.

Pour-flush bowls can also be used to maintain a waterseal. These pans are flushed by hand, using a bucket,and generally require about two litres per flush. Thebiggest disadvantage of this appliance is that theeffectiveness of the flush depends on the humanelement which varies greatly and there is nocontrol over the amount of water used per flush.

The pedestal of an aqua-privy does not have its ownwater seal. The water seal is effected by directing thepipe straight into the digester. No water is needed forflushing, but the level of liquid in the tank must bemaintained.

DESIGN OF

sanitation

Documents

sanitation services

basic sanitation

design of sanitation

human settlement planning

integrated planning

health aspects17disposal

humanrelated data

community participation