V.Lokeesan, BSN

T.Assistant lecturer

FHCS,EUSL.

Objectives

• Water

–Sources and characteristics

–Purpose of water, types of wells

Introduction

• Health care to a community cannot be provided

without ample and safe drinking water

• Health which affects humanity especially in

developing countries is due to lack of safe and

wholesome water

• Water that is easily accessible, adequate in quantity,

should be free from contamination, safe and readily

available throughout the year.

Safe and wholesome water Free from pathogenic agents

Free from harmful chemical substances.

Pleasant to taste i.e., free from colour and odour

and

Usable for domestic purposes

Water is said to be polluted or contaminated

when it does not fulfill the above criteria.

Water requirement• The basic physiological requirements for drinking

water has been estimated at about 2 liters per head

per day.

• A daily supply of 150 – 200 liters per capita is

considered as an adequate supply to meet the needs

for all urban domestic purposes.

• Water should be made available in adequate volume

to reduce the incidence of water related diseases.

Uses of water

The uses of water include:

1. Domestic use: Drinking, cooking, washing, bathing, flushing of toilets, gardening etc.

2. Public Purposes: Cleaning streets, purposes like swimming pools, public fountains, ornamental ponds, fire protect and public parks.

3. Industrial Purpose: Processing and Cooling.

4. Agriculture Purpose: Irrigation

5. Power Production: from hydropower and steam power

6. Carrying of waste: through drainage.

Sources of water supply

There are three main sources of water

1. Rain water

2. Surface water

– Impounding reservoir

– Rivers and streams

– Tanks, ponds and takes

3. Ground water

– Shallow wells

– Deep wells

– Springs

Rain water

Rain is the prime source of all water.

Rain water is the purest in nature:

– Physically - it is clear, bright and sparkling.

– Chemically - it is very soft containing traces of dissolved solids.

– Bacteriologicaly – it is clean and free from pathogenic agents.

The amount of rain water collected will depend upon the rainfall. 1 cm of rainfall over, 1 sq.m will yield 10 liters of water.

Rain water needs to boiled or disinfected if used for drinking.

WATER CYCLE

Surface water

• Surface water originates from rain water. It is the

main source of water supply in many areas.

• Examples of surface water include rivers, tanks,

lakes, man – made reservoirs and sea water.

• Surface water is prone to contamination from

human and animal sources.

• Surface water needs purification before use for

drinking and cooking purposes.

Impounding reservoirs

• These are artificial lakes constructed usually of

earthwork or masonry in which large quantities of

surface water is stored.

• Dams built across rivers and mountain streams also

provide large reserves of surface water.

• The area draining into the reservoir is called

“catchment area”.

• The disadvantage of storing water is the growth of

algae and other microscopic organisms, which impart

bad tastes and odors to water.

IMPOUNDING RESERVOIRS [cont...]

Characteristics

• Impounding reservoirs usually furnish a fairly good quality of water.

• The water is usually clear, palatable and ranks next to rain water in purity.

• The water is usually soft and considered tobe free of pathogenic organisms.

Impurities

• The upland surface water derives its impurities from the catchment area, the sources being human habitations and animal keepig or grazing.

Rivers

Characteristics

• River water is turbid during rainy season; it may be clear in other seasons.

• Clarity of water is no guarantee that river waer is safe for drinking.

• It contains dissolved and suspended impurities of all kinds.

Impurities

• The impurities of river water are derived from surface washings, sewage and sullage water, industrial and trade wastes, and drainage from agricultural areas.

Tanks

• Tanks are large excavations in which surface water

is stored.

• They are an important source of water supply in

some parts of the country.

• Tanks are recipients of contamination of all sorts.

They are full of silt and colloidal matter, especially

after the rains.

• Older tanks may be full of aquatic vegetation.

Ground water

• Rain water percolating into ground water constitutes

ground water.

• Ground water is the cheapest and most practical

means of providing water to small communities.

• Ground water is superior to surface water, because

the ground itself provides an effective filtering

medium.

Ground water [cont...]

ADVANTAGES DISADVANTAGES

It is likely to be free from

pathogenic agents

It is usually requires no

treatment

The supply is likely to be

certain even during dry

season

It is less subject to

contamination than

surface water.

It is high in mineral

content .

It requires pumping or

some arrangement to lift

the water.

Wells• Traditionally wells are the common and main source

of water supply in most areas.

• Technically wells are of two;

i. Shallow wells- tap subsoil water

ii. Deep wells- taps water from the water bearing

stratum

Shallow well Deep well

Definition Taps the water from

above the first

impervious layer

Taps the water from

below the first

impervious layer

Chemical quality Water is moderately

hard

Much harder

Bacteriological

quality

Often grossly

contaminated

pure water

Yield Dry in summer Constant supply

Classified according to method of

construction

• Dug wells

• Tube wells

Sanitary well• This is a well that is properly located, suitably

constructed and well protected from contamination, thus supplying safe water.

• The following important points are to be taken into consideration in constructing safe wells:

i. Location

ii. Lining

iii. Parapet

iv. Platform

v. Drain

vi. Covering

vii. Hand-pump

Sanitary well [cont…]

• Location

– Should be away not less than 15m from sources of

contamination

– Distant between well and the house (<100m)

• Lining

– Lining should be built of bricks or stones set in cement up

to 6 m deep, to allow the water to enter from the bottom

and not from the sides of the well.

– Lining should be curried 60-90cm above the ground

Sanitary well [cont…]

• Parapet wall

– A parapet wall around the well up to the height of at least

(70-75 cm) should be provided above the ground.

• Platform

– Along with the parapet wall the platform should be made

with cement concrete extending at least 1m in all

directions.

– It should have gentle slope outward leading to a drain

built along its edges.

Sanitary well [cont…]

• Drain

– A pucca drain should be built to collect the spilt and dirty

water from the platform of the well and this should be

channeled to a drain or soak pit that is away from the

well.

• Covering

– The top of the well should be covered well by a cement

concrete cover to avoid direct contamination.

Sanitary well [cont…]

• Hand-pump

– A good sanitary well should be equipped with a hand

pump to lift the water in a clean manner.

– When such a facility is not available, it is desirable to

attach a chain and a bucket to the well for the common

use.

Springs

• Ground water comes to the surface and flows

freely under natural pressure

• Two types

– Shallow springs

– Deep springs

REFERENCES

Park,K.(2010). “ Park’s Textbook of Preventive

and Social Medicine”. Ed 20. Bhanarsidoss

Bhanot Publishers, Jabalpur, India.

Rao, K.S. (2004). “An Introduction to

Community Health Nursing”. Ed 4. B.I.

Publications Pvt. Ltd, Chennai, India.