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Spatio-temporal variation in trihalomethanes in New SouthWales5

Richard J. Summerhayes a,e,*, Geoffrey G. Morgan a,d, Douglas Lincoln a,Howard P. Edwards a, Arul Earnest b, Md. Bayzidur Rahman c, Paul Byleveld f,Christine T. Cowie g, John R. Beard a

aUniversity Centre for Rural Health, Northern Rivers, University of Sydney, PO Box 3074, Lismore, NSW 2480, AustraliabCentre for Quantitative Medicine, Duke-NUS Graduate Medical School, SingaporecSchool of Public Health and Community Medicine, University of New South Wales, Sydney, NSW 2052, AustraliadNorth Coast Area Health Service, NSW, Australiae School of Health and Human Sciences, Southern Cross University, Lismore, NSW 2480, AustraliafWater Unit, NSW Department of Health, PO Box 798, Gladesville, NSW 2111, AustraliagRespiratory & Environmental Epidemiology, Woolcock Institute of Medical Research, 431, Glebe Point Road, Glebe, NSW 2037, Australia

a r t i c l e i n f o

Article history:

Received 16 December 2010

Received in revised form

22 August 2011

Accepted 24 August 2011

Available online 1 September 2011

Keywords:

Trihalomethanes

Chloroform

Bromodichloromethane

Drought

Disinfection by-products

Australia

Abbreviations: THMs, trihalomethanes; Tchloromethane; DBCM, dibromochlorometh5 Institution where this work was performe2480, Australia.* Corresponding author. Tel.: þ61 419249037.E-mail addresses: summerhayes.richard

H.Edwards@massey.ac.nz (H.P. Edwards), arhealth.nsw.gov.au (P. Byleveld), christinec@h0043-1354/$ e see front matter ª 2011 Elsevdoi:10.1016/j.watres.2011.08.045

a b s t r a c t

Aim: This paper describes the spatio-temporal variation of trihalomethanes in drinking

water in New South Wales, Australia from 1997 to 2007

Method: We obtained data on trihalomethanes (THMs) from two metropolitan and 13 rural

water utilities and conducted a descriptive analysis of the spatial and temporal trends in

THMs and the influence of season and drought.

Results: Concetrations of monthly THMs in the two metropolitan water utilities of Sydney/

Illawarra (mean 66.8 mg/L) and Hunter (mean 62.7 mg/L) were similar compared to the

considerable variation between rural water utilities (range in mean THMs: 14.5e330.7 mg/L).

Chloroform was the predominate THM in two-thirds of the rural water utilities. Higher

concentrations of THMs were found in chlorinated water distribution systems compared to

chloraminated systems, and in distribution systems sourced from surface water compared

to ground water or mixed surface and ground water. Ground water sourced supplies had

a greater proportion of brominated THMs than surface water sourced supplies. There was

substantial variation in concentration of THMs between seasons and between periods of

drought or no drought. There was a moderate correlation between heavy rainfall and

elevated concentrations of THMs.

Conclusion: There is considerable spatial and temporal variation in THMs amongst New

South Wales water utilities and these variations are likely related to water source, treat-

ment processes, catchments, drought and seasonal factors.

ª 2011 Elsevier Ltd. All rights reserved.

HM4, total THM; NSW, New South Wales; DBP, disinfection by products; BDCM, bromodi-ane.

d: University Centre for Rural Health, Northern Rivers, University of Sydney, Lismore, NSW

@gmail.com (R.J. Summerhayes), geoff.morgan@ncahs.health.nsw.gov.au (G.G. Morgan),ul_earnest@hotmail.com (A. Earnest), bayzid@unsw.edu.au (Md.B. Rahman), pbyle@doh.-ealth.usyd.edu.au (C.T. Cowie).ier Ltd. All rights reserved.

wat e r r e s e a r c h 4 5 ( 2 0 1 1 ) 5 7 1 5e5 7 2 65716

1. Introduction

The provision of safe drinking water through disinfection to

remove water-borne microbiological pathogens causing

typhoid, cholera and gastroenteritis is one of the major

achievements of public (Galal-Gorchev, 1996). An unexpected

consequence of disinfection is the interaction of the disin-

fectant with natural organicmatter (NOM) in the source water

forming a range of chemicals collectively called disinfection

by-products (DBPs) (Rook, 1974).

DBP formation is not well understood but is influenced by

the presence of bromide, iodide, pH, temperature, seasonal

and climatic factors. Operational factors in water treatment

also play a role in DBP formation including residency time

within the distribution system, filtration methods used in

removal of NOM, and disinfectant type and dose (Chowdhury

et al., 2009). Trihalomethanes (THMs) were the first DBPs

discovered in 1974 and are a group of organic compounds

formed through reactions between methane (CH4) derivatives

in NOM and chlorine or chloramines (Garrido and Fonseca,

2010). Since their discovery, more than 600 different DBPs

have been reported, with THMs being the most frequently

detected compounds (Richardson et al., 2007).

In 1976, the US National Cancer Institute declared chloro-

form a carcinogen in animals and a suspected carcinogen in

humans (National Cancer Institute, 1976). Exposure to DBPs is

associated with bladder, rectal and colon cancer, ‘suggestive

of a causal inference’ (Hrudey, 2009).While some reproductive

outcomes such as small for gestational age and pre-term

births have also been associated with DBP exposure, the

current evidence is inconclusive (Grellier et al., 2010). In Aus-

tralia, DBPs are not regulated but a guideline value of 250 mg/L

for total THM is recommended and action to reduce THMs is

encouraged, while not compromising disinfection as exposure

to non-disinfected water poses substantially greater health

risk than exposure to low level THMs (NHMRC, 2004). There is

limited published data describing THMs or other disinfection

by-products in Australia. A survey of several DBPs during

1994-95 in 16 cities throughout Australia found that some

Australian drinking water supplies had high THM concentra-

tions (up to 191 ug/L) (Simpson and Hayes, 1998).

In New South Wales (NSW), Australia’s most populated

state, more than 5million residents (approximately 80% of the

population) use public drinking water as their usual source of

drinking water (Centre for Epidemiology and Research, 2002).

The two largest public water suppliers provide drinking water

to the Sydney/Illawarra (4.2 million people) and Hunter

(516,000 people) metropolitan areas. In rural areas, local water

utilities (largely through local government authorities)

provide drinking water. While the NSW Health Department

recommends that all water utilities collect monthly THM

samples (NSW Health, 2000), only the large metropolitan

utilities of Sydney/Illawarra and the Hunter, and a small

number of rural water utilities conduct regular THM

monitoring.

This paper describes THM concentrations throughout New

South Wales, Australia, covering large metropolitan water

utilities, as well as small to medium size rural water utilities.

Our study assesses geographic differences and temporal

trends in monthly THM data from metropolitan utilities over

several years, and rural utilities for at least one year. During

our study period,much of NSWexperienced one of the longest

droughts on record lasting nearly a decade from 1997 to 2006

(Bond et al., 2008) and we also investigated the influence of

drought on THM’s.

2. Methodology

2.1. Water utility data

We obtained data on THMs for the periods 1998 to 2004 for

Sydney/Illawarra region, 1997 to 2004 for Hunter region and

various time periods between 1997 and 2007 for the rural

water utilities summarized in Table 1.

2.1.1. Sydney/Illawarra water utility dataThe SydneyWater Corporation (SWC) supplies water from five

surface catchments to the Sydney/Illawarra metropolitan

region, covering an area of 12,700 km2. Sydney/Illawarra has

a three level hierarchical structure, with 14 delivery systems

(average area 241 km2) supplied with surface water treated at

nine water filtration plants. Each delivery system contains

from one to six distribution systems (average area 84.3 km2)

which are treated either by chloramination or chlorination.

Rechlorination occurswithin the distribution system.Water is

stored in 180 water supply zones (average area 16.4 km2)

which supply water to homeswithin the distribution systems.

Limited data was also available on a range of water quality

factors and other DBP’s including: trichloracetonitrile (5

months in 1998 covering 18% of supply zones); six haloacetic

acids (HAAs) (two periods of 12 and 7 months covering 69% of

supply zones); and three HAAs (bromoacetic-, dibromoacetic-

and tribromoacetic acids, 5months covering all supply zones).

Due to the limited duration of sampling for these DBP’s, and

the lack of comparable data from other water supplies in

NSW,we have not reported these results in detail in the paper,

but summary statistics are provided in the Supplementary

Material AeC.

There are some 3000 THM water sampling sites within the

Sydney/Illawarra distribution systems. Monthly monitoring is

generally conducted at these sites on a three to six-monthly

rotational cycle with a minimum of 3e6 sites operating

within each distribution system (SWC, 2002). Monthly THM

data from all available monitoring sites within each supply

zonewas averaged to obtain zone/month THM concentrations

for each month in the study period.

2.1.2. Hunter water utility dataThe Hunter Water Corporation supplies the Hunter metro-

politan region via nine water distribution systems covering an

area of 5400 km2. Six distribution systems received surface

water and three received ground water for most of the study

period although prior to 2003 blending of surface and ground

waters from different sources occurred at various time

periods for three distribution systems normally supplied by

surface water. After 2003 two distribution systems, previously

supplied by groundwater, were continuously augmentedwith

Table 1 e Characteristics of NSW metropolitan and rural water utilities included in the study.

Water Utility WaterSource

DisinfectantProcess

Treatment Process(Catchment characteristics)

Approx.pop. (2002)

Number ofsamples

Study Period(months of data)

Sydney/

Illawarra

Surface Chlorinateda Filtration, flocculation,

coagulation, lime.

600,000 5341 Jan 1998eDec 2004 (84)

Chloraminated 3,600,000

Hunterb Surface Chlorinated Filtration, coagulation,

flocculation, sedimentation,

powdered activated

carbon (PAC)

452,000 863 Jan 1997eDec 2004 (96)

Ground Chlorinated Aeration, lime, coagulation,

filtration

60,000

Rural

Utilities

1 Surface Chlorinated Filtration, coagulation,

sedimentation, PAC

4000 28 Feb 2003eNov 2003 (9)

2 Surface Chlorinated Filtration, flocculation,

sedimentation,

21,000 156 Nov 1997eDec 2005 (89)

3 Surface Chlorinated Filtration, coagulation,

flocculation, sedimentation

160,000 72 Nov 2003eJan 2004 (8)

4 Surface Chlorinated Filtration 26,000 314 Jan 2001eMay 2007 (62)

5 Surface Chlorinated No treatment 65,000 508 Jan 2001eDec 2004 (54)

6 Surface

blended

Chlorinated Lime, aeration 2000 61 Jan 2001eMay 2006 (61)

7 Surface Chlorinated Coagulation, flocculation,

sedimentation

20,000 30 Jul 2001eJan 2004 (30)

8ac Ground Chloraminated Direct filtration, aeration,

coagulation, flocculation,

dissolved air flotation

4500 1378 Dec 2000eMay 2006 (63)

8bc Surface Chlorinated Filtration, coagulation,

flocculation, sedimentation

11,000 660 Dec 2000eMay 2006 (66)

9 Surface Chlorinated Direct filtration 21,000 85 Jan 2000eOct 2006 (80)

10 Surface Chlorinated Direct filtration, coagulation,

flocculation, sedimentation

53,000 43 Jun 2001eAug 2005 (40)

11 Surface Chlorinated Filtration, dissolved air

flotation, flocculation

74,000 1610 Jan 2000-Apr 2006 (61)

12 Surface Chlorinated Filtration, flocculation 8000 43 FebeDec 2003 (11)

13 Surface Chlorinated Filtration, coagulation,

flocculation, sedimentation

135,000 159 Mar 1999eJan 2006 (86)

a In Sydney/Illawarra, 4 of the 33 distribution systems changed disinfection from chlorination to chloramination in June 2003.

b In Hunter, two distribution systems using ground water were augmented with ground and surface waters from other sources after 2003, and

prior to 2003, some systems supplied with surface water were occasionally augmented with blended ground and surface waters from other

sources.

c Water utility 8 includes a chloraminated distribution system with ground water supply (8a) and a chlorinated distribution system with

a surface supply. Data for 8a should be treated with caution as majority of values were below <5 mg/L detection limit.

wat e r r e s e a r c h 4 5 ( 2 0 1 1 ) 5 7 1 5e5 7 2 6 5717

blended surface and ground water from different sources

(HWC, 2004). A fixed sampling site is located within each

distribution system towards the extremities of the systems,

providing distribution/month THM values.

2.1.3. Rural water utility dataWe surveyed all 106 utilities in rural NSW requesting infor-

mation and data on DBPs and water quality parameters.

Ninety-four rural water utilities (89%) responded to the survey

and 27 (26%) indicated they collected some data on THMs. We

received data on THMs from 25 (24%) rural water utilities of

which 13 (12%) had sufficient THM data to be included in our

analysis. Five of these rural utilities supplied additional

monitoring data on a range of other water quality parameters,

however these data covered limited durations and were

insufficient to assess seasonal trends and geographic differ-

ences and in keeping with the objectives of the paper are not

reported in detail, although they are briefly summarised in the

Supplementary Material A.

The size and complexity of rural water utilities varies, and

THM sampling varied from one-off short term sampling

periods to routine quarterly or monthly sampling covering

various time periods between 1997 and 2007 (see Table 1). All

sampling was conducted at random sites throughout the

distribution systems. Water utility #6 provided data only on

THM4 from sample points within the distribution system. A

separate one-month survey in utility #6 including post-

treatment samples indicated that chloroform comprised

approximately 86% and BDCM 13% of the THM4 concentration

entering the distribution system (these survey data not

included in the final analysis but are provided in

Supplementary Material D). Rural utility #8 includes a distri-

bution system which is chloraminated and mainly sourced

from ground water, and a chlorinated distribution system

wat e r r e s e a r c h 4 5 ( 2 0 1 1 ) 5 7 1 5e5 7 2 65718

sourced from surface water. We designated the two distribu-

tion systems as #8a and #8b respectively for reporting. The

source water, disinfection, treatment types, number of THM

samples and sampling period for each of the water utilities

included in our analysis are shown in Table 1.

We included only those rural water utilities with monthly

monitoring data covering all four seasons in at least one year

(DecembereFebruary ¼ summer, MarcheMay ¼ autumn,

JuneeAugust¼winter and SeptembereNovember¼ spring) so

that seasonal variation could be assessed. For each rural water

utility with sufficient data to be included in the study we

averaged available monthly THM concentrations to obtain

utility/month concentrations.

2.1.4. Trihalomethane monitoringWater samples were analysed for THMs by Sydney Water

Corporation laboratories using Standard Methods for the

Examination of Water and Waste Water (20th Ed.), Method

6200B (modified) and USEPA Method 8260 (modified) (APHA-

AWWA-WPCF, 1998; USEPA, 2008); in the Hunter Water

Corporation based on the USEPA standard Method 8260

(USEPA, 2008) and in rural water utilities using the Standard

Methods for the Examination of Water andWasteWater (18th

ed) Method 6232 (APHA-AWWA-WEF, 1992). Further details of

the analytical techniques are provided in the Supplementary

Material E.

Multiple values below the detection limit were recorded

within each water utility over the study period. The limit of

detection for individual THMs was usually <1 mg/L, with

occasional higher limits of detection reported. We used

a similar approach to other studies and substituted samples

flagged as below the detection limit with two-thirds of the

detection limit value, which is the approximatemean of a log-

normal distribution (Whitaker et al., 2003). Bromoform was

found to be below the detection limit more than 75% of the

time across most utilities (metropolitan and rural), and

therefore we examined bromoform only as part of total

brominated THMs (BrTHM) and the sum of the four trihalo-

methanes (THM4) (percentage of observations below detec-

tion values provided in Supplementary material F).

2.2. Rainfall data

Data on rainfall was obtained from the Sydney Catchment

Authority, and the Australian Bureau of Meteorology website

(Bureau Of Meteorology, 2010). Data on monthly drought

status for NSW districts containing the water utilities was

obtained from the NSW Department of Primary Industries,

with each month classified as ‘no drought’, ‘marginal’ or

‘drought’. Drought status is defined by a number of criteria

including monthly rainfall, temperature, frost and evapora-

tion, poor pasture biomass, soil moisture and livestock.

Marginal conditions include rainfall for the previous 3months

within or below average for the three month rainfall decile

and surface water supplies less than 50% of normal for the

time of year. Drought conditions include rainfall for the

previous 6 months within or below average for the 6-month

rainfall decile and surface water supplies less than 30% of

normal for the time of year (NSW Department of Primary

Industries, 2010).

2.3. Statistical analysis

We produced a range of descriptive statistics using log

transformed THM concentrations due to the skewed THM

distribution and back-transformed the results for reporting.

Differences in themeans for season and drought periods were

assessed using KruskaleWallis tests. Correlations between

THMs and rainfall lagged up to one month were conducted

using the Spearman correlation coefficient. The selection of

a one month lag is based on a 30e40 day residency time for

Prospect Reservoir in the Sydney/Illawarra supply (Hamilton

et al., 1995). Data management was conducted in Excel

(version 2003) and Access (version 2003) and all statistical

analyses were conducted using SAS version 9.1.3 (SAS Insti-

tute Inc., Cary North Carolina USA).

3. Results

3.1. Spatial variation

Table 2 summarises descriptive statistics for individual THMs

and THM4 concentrations in treated water for all the selected

NSW water utilities. The mean THM4 concentrations in Syd-

ney/Illawarra (66.8 mg/L) and Hunter are similar (62.7 mg/l).

Water treated by chlorination in Sydney/Illawarra had higher

mean THM4 concentrations (81.1 mg/L) than water treated by

chloramination (50.8 mg/L). The Prospect South delivery

system in Sydney/Illawarra switched from chlorination to

chloramination in July 2003 and the mean monthly chloro-

form concentration decreased substantially from 59.5 mg/L

during the chlorination period (1998 to mid-2003) to 23.0 mg/L

( p < 0.001) during the chloramination period (mid-

2003e2004). In the Hunter, chlorinated surface water had

higher mean THM4 concentrations (74.4 mg/L) than chlori-

nated ground water (36.1 mg/L). From 2003, Hunter augmented

two ground supplies and three surface supplies continuously

with blended ground and surface waters in response to

drought conditions. The mean THM4 in the ground water

supplies increased from 17.9 to 40.6 mg/L with augmentation

and from 66.4 to 74.2 mg/L in the surface supplies.

The majority of the rural water utilities reporting in the

study use chlorination, one system used chloramination

together with chlorination. Rural NSW water utilities gener-

ally use surface water, with some using ground water or

a blend of ground and surface waters. During the study period

there was large variability in the monthly mean THM4

concentration in treated water between rural water utilities.

The THM4 concentration of the rural utility with the

minimum (#8a: 15 mg/L) and maximum (#6: 331 mg/L) monthly

concentrations were substantially different compared to the

remaining 11 utilities which ranged from of 63.7 mg/L to

189.1 mg/L, although this trimmed range still represents a 3

fold difference in monthly THM4 concentrations.

Chloroform is the main component of total THM in chlo-

rinated (66%) and chloraminated (59%) surface water in Syd-

ney/Illawarra. Chloroform is also themain component of total

THM in chlorinated surface water in the Hunter (60%) and in

most rural utilities with the exception of utilities #2 (29%), #3

Table 2 e Concentrations of trihalomethanes in treated drinking water in water utilities in New South Wales.

Water Utility N Mean THM4 Chloroform BDCM DBCM

Min P95 Max Mean Min Max Mean Min Max Mean Min Max

Metropolitan

Sydney/Illawarra 563 66.8 22.7 114.6 196.7 40.1 4.5 162.5 16.5 3.0 46.0 7.1 0.7 27.3

Chloraminated 278 50.8 22.7 81.3 199.0 28.3 9.0 88.0 14.2 3.0 39.0 5.8 0.7 31.0

Chlorinated 340 81.1 25.0 127.0 196.7 50.7 4.5 162.5 18.6 5.7 46.0 8.1 0.8 27.3

Hunter 72 62.7 10.1 105.2 114.6 35.2 0.7 96.3 15.2 0.7 31.2 9.1 0.9 24.9

Ground 18 36.1 10.1 74.3 74.3 16.0 0.7 46.8 8.3 0.7 20.8 5.9 2.8 9.2

Blended 30 72.6 14.7 106.4 134.0 33.4 1.0 78.3 20.7 0.7 34.3 15.2 3.7 27.0

Surface 48 74.4 30.1 105.2 131.0 44.5 20.5 96.3 18.1 3.1 30.0 10.0 0.9 24.0

Rural Utilities

1a 9 189.1 67.5 290.7 290.7 104.8 29.7 190.1 48.8 22.5 94.1 19.8 4.7 76.3

2 89 114.9 21.0 231.0 346.0 33.6 2.0 172.0 32.5 4.5 104.7 32.7 2.8 128.5

3 8 81.7 65.4 102.3 102.3 29.5 13.3 47.9 24.9 20.6 31.2 16.6 6.9 24.7

4 62 106.1 21.1 170.2 245.4 45.0 16.8 108.8 26.8 0.7 56.7 16.0 0.7 56.7

5 54 73.4 23.8 120.1 122.3 48.2 13.9 90.0 16.5 6.3 24.2 5.7 2.7 10.3

6a 61 330.7 63.0 501.0 586.0 na na na na na na na na na

7 30 87.5 22.7 147.3 213.7 72.8 3.0 200.0 11.9 3.0 20.0 1.4 1.0 2.0

8a 63 14.5 13.1 17.8 23.6 4.4 3.3 11.2 3.4 3.3 5.4 3.3 2.5 4.1

8b 66 102.2 44.9 145.4 221.2 63.9 22.2 159.2 25.6 8.2 51.3 9.1 3.3 25.3

9 80 99.3 39.0 157.9 180.0 46.8 12.0 112.8 33.4 12.0 57.0 17.9 8.0 56.0

10 42 63.8 13.3 86.3 120.0 34.1 3.3 68.0 16.2 3.3 39.0 9.5 1.0 32.0

11 61 63.7 18.4 102.3 128.9 33.0 5.7 86.6 16.6 3.8 32.2 9.2 3.3 32.0

12a 11 138.5 52.3 286.0 286.0 87.1 17.3 155.0 31.3 13.3 78.0 12.3 1.3 48.0

13 86 94.9 2.7 152.7 229.0 54.5 0.7 110.0 26.7 0.7 76.0 11.1 0.7 64.0

All values in mg/L ¼ micrograms per litre, N ¼ number of observations, Min ¼ minimum, P95 ¼ 95th percentile, Max ¼ maximum, na ¼ not

available.

Sydney/Illawarra mean: mean of annual zone means.

Hunter mean: mean of annual distribution system means.

Rural water utilities mean: mean of monthly utility means.

Water utility 8 includes a chloraminated distribution systemwith groundwater supply (8a) and a chlorinated distribution systemwith a surface

supply. Data for 8a should be treated with caution as majority of values were below <5 mg/L detection limit.

Water utility 6 only has data for THM4.

a Utilities with 95th percentile THM4 concentrations above the Australian National Drinking Water Guideline value of 250 mg/L.

wat e r r e s e a r c h 4 5 ( 2 0 1 1 ) 5 7 1 5e5 7 2 6 5719

(36%) and in the ground water sources in the Hunter (56%) and

#8a (30%) which had higher proportions of brominated THMs.

3.2. Rainfall

Fig. 1 illustrates the temporal variation in Sydney/Illawarra

chloroform and brominated THM concentrations and mean

monthly rainfall. Prior to October 1998 brominated THM

concentrations were generally higher than chloroform, then

decreased until mid 1999 and have since remained relatively

constant. Chloroform concentrations decreased steadily from

mid-1998 but showed considerable variability, and from late

2003 concentrations were similar or lower than brominated

species. Several peaks and troughs in chloroform concentra-

tion coincidewith heavy rainfall events.We found amoderate

correlation between overall monthly THM4 and rainfall (lag

one month, r ¼ 0.35, p < 0.01) for the Sydney/Illawarra, with

higher correlations within some of the five Sydney/Illawarra

catchments (Blue Mountains/Cascade catchment: r ¼ 0.57,

p < 0.001; Upper Nepean/Illawarra catchment r ¼ 0.47,

p < 0.001).

Fig. 2 shows the temporal variation in chloroform, bromi-

nated THMs and rainfall in the Hunter region. Chloroform

concentrations are generally higher than brominated THMs,

with occasional large peaks in chloroform and brominated

THMs from2001.We found no correlation in theHunter region

between rainfall (lag one month) and mean THM concentra-

tion in distribution systems supplied by ground water, and

a moderate correlation in distribution systems supplied by

surface waters (r ¼ 0.59, p < 0.01).

We generally foundmoderate correlations between rainfall

and THM4 concentrations in the rural utilities located in sub-

tropical coastal floodplains including utilities #11 (r ¼ 0.30,

p < 0.02), #8b (r ¼ 0.58, p < 0.001) and #5 (0.67, p < 0.001). We

generally found little correlation with mean monthly rainfall

(lag 1 month) and THM in the other rural utilities (data not

shown).

3.3. Drought

We examined the difference in the concentration in THMs in

periods of drought compared to marginal and no drought and

the results are summarised in Table 3. Sydney/Illawarra was

in drought for 18 months (21.4%) of the 84 month study period

and continuously in marginal drought from September 2002

until mid-2007. There was a consistent significant decrease in

mean THM4 concentrations during drought months

compared to non-drought (THM4: 52.6ug/L compared to

0.0

20.0

40.0

60.0

80.0

100.0

120.0

0

10

20

30

40

50

60

70

80

90

Mea

n M

onth

ly C

atch

men

t R

ainf

all (

mm

)

Mea

n M

onth

ly C

hlor

ofor

m a

nd B

rom

inat

ed T

HM

C

once

ntra

tion

(ug

/L)

BrTHM Chloroform Rainfall

Fig. 1 e Temporal variation in Sydney/Illawarra monthly chloroform and brominated THM concentration and monthly

rainfall.

wat e r r e s e a r c h 4 5 ( 2 0 1 1 ) 5 7 1 5e5 7 2 65720

75.9ug/L, p < 0.001), and this was reflected in chloroform and

BDCM, while DBCM concentration increased. The majority of

sampling for HAAs in Sydney/Illawarra occurred in a non-

drought period, however three HAAs (bromoacetic-;

dichloroacetic- and trichloroacetic acids) showed significant

decline during drought compared to no drought consistent

with reductions in THMs, except DBCM (see Supplementary

Material C).

Hunter was in drought for 19months of the 96month study

period and only the blended distribution systems showed

a significant THM4 decrease during drought compared to no

drought (THM4: 69.8 mg/L compared to 46.4 mg/L, p < 0.05), re-

flected in chloroform, BDCM and DBCM. THM concentrations

0

10

20

30

40

50

60

70

80

90

100

Mea

n M

onth

ly C

hlor

ofor

m a

nd B

rom

inat

ed T

HM

C

once

ntra

tion

(ug/

L)

chloroform BrTHM Rainfall

Fig. 2 e Temporal Variation in Hunter monthly chloroform and

rainfall (mm).

in rural water utilities during drought periods compared to

non-drought periodswere extremely variable. Five rural water

utilities that were in drought continuously for 12 months or

longer experienced significantly reduced chloroform concen-

trations compared to periods of no drought (#2, #4, #9, #10 and

#13), and these same utilities experienced significantly

increased DBCM concentrations.

3.4. Seasonal variation

We found considerable seasonal variability in mean THM4

concentrations between locations and these results are sum-

marised in Table 4. In Sydney/Illawarra there was a significant

0

50

100

150

200

250

300

350

400

450M

ean

Mon

thly

Cat

chm

ent

Rai

nfal

l (m

m)

brominated THM (BrTHM) concentration and monthly

Table 3 e Mean monthly trihalomethane concentrations during drought compared to no drought and marginal drought, NS water utilities.

Water Utility Time (months THM4 Chloroform BDC DBCM

NoDroughtn (%)

Marginaln (%)

Droughtn (%)

NoDroughtMean

MarginalMean

DroughtMean

NoDroughtMean

MarginalMean

DroughtMean

NoDroughtMean

Margi alMea

DroughtMean

NoDroughtMean

MarginalMean

DroughtMean

Sydney/Illawarra 50 (59.5) 16 (19.1) 18 (21.4) 75.9 51.1 52.6** 49.0 27.5 27.6** 17.7 13. 14.1** 6.6 7.4 8.0**

Chloramination 59.4 37.0 36.5** 36.0 17.4 16.5** 16.1 11. 11.4** 5.3 6.3 6.6**

Chlorination 87.2 66.7 67.8** 57.8 38.7 37.9** 18.8 16. 16.7** 7.5 8.7 9.4**

Hunter 60 (62.5) 17 (17.7) 19 (19.8) 58.4 73.6 66.4* 33.2 41.6 35.4 13.9 18. 17.0 8.2 10.7 10.6

Ground 31.5 56.1 50.2** 12.5 22.9 20.7** 6.8 16. 14.4** 5.9 11.6 9.8**

Blended 69.8 70.6 46.4* 36.7 35.4 19.0** 20.0 19. 11.6* 11.5 12.1 9.9

Surface 72.3 84.2 80.6* 46.4 54.5 47.5 16.1 18. 20.0** 8.4 9.5 11.2*

Rural Utilities

2 26 (27.1) 19 (19.8) 51 (53.1) 149.9 97.6 113.5* 55.6 36.8 25.3* 32.6 32. 30.9 32.4 23.2 36.6*

3 1 (12.5) 4 (50.0) 3 (37.5) 67.4 86.7 88.8 14.3 30.8 39.4 22.7 26. 26.7 20.2 21.9 17.2

4 10 (16.1) 5 (8.10) 47 (75.8) 151.2 134.5 103.8* 92.3 92.9 41.0* 21.8 30. 31.2 5.8 11.6 22.2*

5 24 (44.4) 16 (29.6) 14 (25.9) 74.8 81.3 82.6 49.2 56.9 57.7 17.7 17. 17.6 7.2 6.7 7.2

6 23 (37.7) 20 (32.8) 18 (29.5) 287.5 379.3 331.9** a a a a a a a a a

7 12 (40.0) 6 (20.0) 12 (40.0) 86.0 89.2 88.1 74.3 74.3 70.6 9.1 12. 14.8** 1.3 1.6 1.5

8b 24 (36.4) 7 (10.6) 35 (53.0) 97.1 108.8 105.9 56.8 70.9 68.9 26.8 26. 25.3 10.1 8.3 8.7

9 29 (36.2) 16 (20.0) 35 (43.8) 100.4 97.3 100.3 54.8 40.5 43.7* 32.5 34. 33.6 12.7 20.2 21.1**

10 10 (25.0) 7 (17.5) 23 (57.5) 63.7 56.9 67.5 48.3 29.5 30.6* 9.5 15. 19.7* 2.6 8.7 13.0**

11 38 (62.3) 15 (24.6) 8 (13.1) 63.4 69.0 71.9 33.5 39.7 34.0 16.9 18. 18.6 9.6 8.8 14.8

12 - (0.0) 1 (09.0) 10 (91.0) na 157.9 143.1 na 135.0 94.1 na 20. 33.8 na 1.3 14.1

13 47 (54.7) 22 (25.6) 17 (19.8) 83.9 112.7 104.5* 50.7 67.5 48.5* 22.9 33. 31.3* 9.4 10.4 18.7*

* Significant at p < 0.05 level.

** Significant at p < 0.001 level, na e no data were available Means are reported in mg/L.

Water utility #12 was in marginal or drought only.

Water utilities #1 and #8a not shown as utility #1 was continuously in drought during the study period and water utility #8a values were below thre old and showed no variation between themeans.

a Water utility #6 reported THM4 data only.

water

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Table 4 e Seasonal variation in the mean trihalomethane concentration in water utilities in New South Wales.

Summer Mean THM4 Autumn Mean Winter Mean Spring Mean Summer-Winter Difference (%)

Sydney/Illawarra 69.9 72.6 64.3 60.3 þ5.6 (9.0)

Chloramination 54.8 58.0 54.0 52.0 þ0.8 (1.5)

Chlorination 80.0a,byy 79.3a,byy 71.9 69.8 þ8.1 (11.3)

Hunter 60.8 66.8 60.5 62.5 þ0.3 (0.5)

Ground 34.2 39.6 39.5 39.8 5.3 (15.5)

Blended 43.1a,cy 74.8 66.7 63.1 23.6 (54.8)

Surface 75.4 80.6 77.4 71.5 þ2.0 (3.0)

Rural Utilities

1 233.7 183.6 165.4 189.3 þ68.3 (41.3)

2 146.0ay 112.3 90.9 104.8 þ55.1 (60.6)

3 82.0 66.2 90.2 79.7 8.2 (9.1)

4 110.8 122.5a,y 87.4 86.0 þ23.4 (26.8)

5 89.7ayy 85.5ay 46.2 62.0 þ43.5 (94.2)

6 340.9 313.8 324.3 345.1 þ16.6 (5.1)

7 80.5 96.9 77.1 97.8 þ3.4 (4.4)

8b 124.1ayy 107.0ay 79.8 91.3 þ44.3 (56.5)

9 97.6 102.2 99.5 97.7 1.9 (1.9)

10 64.1 70.7 60.1 64.2 þ4.0 (6.7)

11 72.1ay 67.3 48.7 58.1 þ23.4 (48.0)

12 212.5 129.2 89.5 126.1 þ123.0 (137.4)

13 93.7 92.0 97.3 94.7 3.6 (3.7)

Means and difference between summer and winter means are reported in mg/L.

y significant at the p < 0.05 level.

yy significant at the 0.001 level.

Water utility 8a values were below threshold and showed no variation between the means.

a Difference in means compared to winter.

b Difference in means compared to spring.

c Difference in means compared to autumn.

wat e r r e s e a r c h 4 5 ( 2 0 1 1 ) 5 7 1 5e5 7 2 65722

increase ( p < 0.001) in mean THM4 concentration in chlori-

nated water during summer (mean 80.0 mg/L) compared to

winter (mean 71.9 mg/L) and spring (69.8 mg/L), but therewas no

difference in chloraminated distribution systems. In the

Hunter THM4 concentrations in blended water increased

significantly ( p < 0.05) by 23.6 mg/L in winter compared to

summer, while therewas generally a small increase in surface

and ground water concentrations. There was substantial

variation in the seasonality of THM4 concentrations between

rural water utilities. Ten of the 13 rural water utilities had

higher mean THM4 concentrations in summer compared to

winter ranging in increases of 4e123 mg/L, and this increase

was significant ( p < 0.05) in four utilities.

4. Discussion

4.1. Spatial variation

We found the concentration of THM4 and speciation to be

similar for the Sydney/Illawarra (THM4 ¼ 67 mg/L, 60% chlo-

roform) and Hunter (THM4 ¼ 63 mg/L, 56% chloroform)

metropolitan water utilities.

We found considerable variation in THM concentrations

and speciation between rural water utilities, with mean

monthly THM4 concentrations ranging from 15 to 331 mg/L

(29e86% chloroform). The THM4 concentration of the rural

utility with the minimum (#8a: 15 mg/L) and maximum (#6:

331 mg/L) in the rangewere substantially different compared to

the remaining 11 utilities and suggests that the factors influ-

encing THM4 concentrations in utilities #8a and #6 are

substantially different to the other 11 rural utilities. Differ-

ences in geography and catchment characteristics may

contribute to variation in THM concentrations throughout

NSW. Utilities in the semi-arid floodplains in the far-west of

the State (#1, #2 and #12) had higher THM4 concentrations

(range of means: 114e189 mg/L) compared to other water

utilities (range of means: 15e106 mg/L) with the exception of

water utility #6 (mean 331 mg/L) which is in a sub-tropical

coastal floodplain area. The 95th percentile for THM4

concentration for three rural water supplies was above the

Australian guideline value of 250 mg/L (Table 2) suggesting

these utilities need to implement strategies to reduce THM

concentrations (NHMRC, 2004).

The Australian guideline value for THM4 of 250ug/L is

higher than a number of other developed countries including

United Kingdom, Japan (100 mg/L), USA (80 mg/L) France

(30 mg/L) and Germany (10m/L) (Rizzo et al., 2005). The large

variation in mean THM4 in rural NSW is similar to that re-

ported in a survey of DBPs in North Virginia, USA prior to the

introduction of the 1979 interim Disinfection By-Product Rule

of <100 mg/L (USEPA, 1979) which found mean THM4

concentrations of 249 mg/L (range 40e531 mg/L) in 1975e76 and

173 mg/L (range 43e889 mg/L) in 1976e77 (Hoehn and Randall,

1979). In a study in Turkey, where THMs are not regulated,

mean THM4 concentrations of 159 mg/L and 129 mg/L were

reported (Rizzo et al., 2005). Similar large variation has also

been found in rural communities in Alberta, Canada during

wat e r r e s e a r c h 4 5 ( 2 0 1 1 ) 5 7 1 5e5 7 2 6 5723

Autumn 2000 with mean THM3 (excluding bromoform)

ranging from 44m/L to 210m/L (Charrois et al., 2004).

THM4 levels in NSW utilities were generally higher than

levels found in countrieswhere THMs are regulated. A 1988-89

survey reported median THM4 value of 39 mg/L for 35 utilities

across the USA (Krasner et al., 1989). A survey of 113 systems

in North Carolina in 2004-05 reported an average THM4 of

40.8 mg/L. In the United Kingdom, a study of data from 1992 to

1996 reported mean THM4 concentrations of 46 mg/L (Keegan

et al., 2001).

Chloroform generally comprised the majority of the total

THM in treated surface water in NSW (52%e86%). The domi-

nation of brominated THMs in treated ground water in the

Hunter (56%) and rural utility #8a (70%) is likely due to the

coastal aquifers having higher levels of bromide compared to

the surface supplies (Kampioti and Stephanou, 2002). The

surface water supplies of utility #3 (64% brominated THMs)

lies in a coastal floodplain area which may be affected by

saltwater intrusion; while utility #2 (71% brominated THMs)

lies in an ancient sea-bed which has been noted to have high

bromide concentrations (Richardson, 2005).

Chloraminated systems generally had lower THM4

concentrations (utility #8a mean THM4 14.5 mg/L, Sydney

mean THM4 50.8 mg/L) than chlorinated systems. A change

treatment from chlorination to chloramination in a delivery

system in Sydney resulted in a 159% reduction in THM4.

Bougeard et al. (2010) in a 2008 study in the United Kingdom

reported a 92% reduction in THM4 with a shift in disinfection

from chlorination to chloramination.

A major strength of this study lies in the large number of

observations covering a lengthy time period, incorporating

periods of long-term drought, drought-free periods and heavy

rainfall events. While we were only able to access THM data on

a small proportion of the total number of rural NSWwater util-

ities the surveyed utilities cover a wide range of geographic and

climatic regions encountered across the Australian continent.

4.2. Seasonal variation

We found substantial seasonal variation in THM4 concentra-

tions in chlorinated water in Sydney/Illawarra and in many of

the rural NSW water utilities, with generally higher concen-

trations in summer/autumn and lower concentrations in

winter, especially in semi-arid locations in the far-west of NSW

(utilities #1, #2 and #12). The groundwater supplied systems in

the Hunter showed little THM variation between seasons and

these results are consistent with overseas studies. A Canadian

survey of THMs showed amore than two-fold variation during

summer and winter in chlorinated systems (62.5 mg/L

compared to 33.5 mg/L) and chloraminated systems (32.8 mg/L

compared to 13.7 mg/L), however in groundwater supplies there

was little variation between seasons (Williams et al., 1995).

Another study in China in 2003 found THM levels to be 50 mg/L

in autumn and around 10 mg/L in spring in chloraminated

waters and noted variations in different organic matter

concentrations and in the dynamics of algae/plankton

production in the different seasons (Chen et al., 2008).

Summer is considered the most challenging period for

treating water and maintaining water quality and the

magnitude of seasonal fluctuations may be dependent on the

water source (McGuire and Meadow, 1988).

4.3. Rainfall

Several peaks and troughs in chloroform concentration coin-

cide with heavy rainfall events in Sydney/Illawarra. One such

event was the rains in mid 1998 that broke a drought lasting

from 1992 to 1998 and resulted in large inflows of contami-

nants and organic matter into the Sydney/Illawarra catch-

ment (Cox et al., 2003). The moderate correlations found

between rainfall and THM reported in our results are consis-

tentwith the correlations found in aNorth Virginia, USA study

(Hoehn and Randall, 1979). Heavy drought breaking rainfall is

associatedwith high turbidity, increased inflows, soil leaching

of NOM and microbiological contamination from degraded

catchments (Stein, 2000).

4.4. Drought

Droughts lasting several months to several years are a regular

feature of the Australian environment. Much of NSW experi-

enced one of the longest droughts on record lasting nearly

a decade from 1997 to 2006 (Bond et al., 2008). Sydney and parts

of NSW experienced drought from 1992 to 98 with a significant

wet period in mid-1998, then entered into drought again from

2002 until early 2011. During this period the Sydney catchment

storage (2 million megalitres) fell from 91% in 2000 to 32.5% in

mid-2007, in some rural catchments water levels fell below

30%, whereas the Hunter maintained a storage capacity above

60% by augmenting its water supply from 2002 with ground

and surface water from additional sources in response to

drought conditions (HWC, 2004). Inflows into major river

systems in NSW were some of the lowest on record and some

floodplains and wetlands had not been flooded during the

decade of drought (Murphy and Timbal, 2008).

While the effects of drought were variable, Sydney/Ill-

awarra and five of the 13 rural utilities experienced consistent

decrease in chloroform and an increase in DBCM during

drought periods. The effect of drought was also evident in

both chlorinated and chloraminated water as illustrated by

decreased chloroform concentrations in the Prospect South

distribution system during periods of drought when the

system was chlorinated and when it changed to being chlor-

aminated. The blended water distributions systems in the

Hunter showed decreased THM concentrations during

drought periods, while the ground and surface water systems

showed increased THM concentration.

Our findings in NSW are broadly similar to a UK study that

also that found decreases in chloroform concentration in

water supplies during drought (Whitaker et al., 2003). A study

in Greece showed a lower mean chloroform concentration

during an intense drought period (2.27 mg/L) compared to no

drought (10.22 mg/L) and an increased mean DBCM concen-

tration (drought 13.76 mg/L; no drought 1.38 mg/L) from

increased bromide through saltwater intrusion and ground

water augmentation (Kampioti and Stephanou, 2002). A North

Virginia, UAS study reported a large variation in THMs during

a period of no drought from 1975 to 76 (mean THM4 249 mg/L)

compared to severe drought from June 1976 to November 1977

wat e r r e s e a r c h 4 5 ( 2 0 1 1 ) 5 7 1 5e5 7 2 65724

(mean THM4 173 mg/L). Themean concentration of chloroform

decreased from 246 to 152 mg/L in the drought compared to no

droughtwhile a small increase in BDCM from 19 to 21 mg/Lwas

reported (Hoehn and Randall, 1979). Drought can cause long-

term variations in DBP formation and the 1997-98 US Infor-

mation Collection rule survey found that long-term seasonal

factors such as drought, flood, hurricanes may account for

seasonal variation in water quality both in the source water

and in the distribution system although this was not assessed

in detail (McGuire et al., 2002).

Our results support previous findings that seasonal and

long-term effects of drought can have complex effects on the

nature and presence of NOM resulting in either an increase or

decrease in NOM which may in turn affect the nature and

concentration of THMs, suggesting that the effects of drought

may be catchment specific (Williamson et al., 1999). Algal

blooms, common in Australian waters may also play a large

role during warmer months and periods of low rainfall. Algal

blooms have been correlated with THM levels and regarded as

an important precursor for DBP production (Hoehn and

Randall, 1979; Chen et al., 2008). Although we had no data on

algae levels, algal blooms occurred in several rural water

utilities in coastal floodplain/estuarine areas (utilities #3, #6,

#13) and sub-tropical coastal areas (#11, #8b) during warmer

months and periods of low rainfall and drought. The

concentration of chloroform in all these surface supplied

distribution systemswas higher during drought periods. Rural

utility #6 suffered a number of major algal blooms during the

study period and recorded the highest concentrations of

THM4 amongst the study locations.

A decrease in organic matter can occur during drought due

to reduced run-off from catchments and inflows, which can

lead to lower turbidity and settling of sediments and organic

matter (Bond et al., 2008; Murphy and Timbal, 2008). Degra-

dation of organic matter over time during lengthy dry periods

and slower travel time of water compared to wet events can

also reduce organics in the water (Personal communication

Sydney Catchment Authority 2011). Drought can also influ-

ence groundwater quality due to declines in aquifer levels and

increased salinity causing bromide concentrations to rise

which can affect THM speciation (Krasner et al., 1994).

While there is much speculation on the effects of climate

change on drinking water quality (Bates et al., 2008), increases

in the frequency and extent of drought affected areas and

flooding from drought breaking rains are expected in south

eastern Australia (ABS, 2008; Dore, 2005). Water treatment

authorities respond to the higher risk of microbial contami-

nation of the raw source water during or shortly after heavy

rainfall by using higher disinfectant concentrations which in

turn can promote THM formation (Eikebrokk et al., 2004).

Changes in climatic factors related to climate change are

likely to create additional operational challenges for water

utilities in Australia, particularly in rural areas of NSW with

limited resources (Hurst et al., 2004; Soh et al., 2008).

5. Conclusion

We found considerable variation in THM concentration

between rural water utilities in NSW with some utilities

experiencing elevated concentrations above current national

THM4 guideline values indicating that these utilities require

action to reduce THM’s, while not compromising disinfection.

We obtained THM data from a small proportion of rural NSW

water utilities and our results suggests that elevated THM4

concentrations may occur in water utilities across rural NSW,

and rural Australia. THM concentrations in the chloraminated

systems in Sydney and the one rural utility were generally

lower than the chlorinated water supply systems.

We found considerable variation in THM’s between and

within utilities associated with extended drought periods

experienced during our study, with some utilities showing

decreases in chloroform and BDCM and increases in DBCM.

While we generally found higher concentration of THMduring

the warmer compared to cooler months the overarching

influence of drought on THMsmakes it difficult to identify the

principal drivers. Unfortunately our data lacked detailed data

on NOM, algae and catchment characteristics and inflows

which may help understand the possible drivers for these

variations.

The Australian Drinking Water Guidelines are currently

under review and at this time no change has been proposed to

the guideline value of 250 mg/L for THM4 (NHMRC, 2009). The

Guidelines note that a high concentration of THM4 is a good

indicator that other DBPs may be present. However data on

the occurrence, nature and concentrations of other DBPs are

scarce due to the lack of comprehensive survey data in NSW

and Australia. We recommend improved monitoring and

reporting of DBP’s and the collection of good data on catch-

ment characteristics and treatment to enable the assessment

of contributing factors to elevated concentrations of DBPs,

especially in rural Australia.

Competing financial interests

None identified.

Acknowledgements

The authors would like to acknowledge the following organi-

sations and individuals for their work on this manuscript:

Dr Mark Angles, Dr Peter Cox, Dr Vicky Whiffin, Mr David

Holland from Sydney Water Corporation and Adam Lovell

fromWater Services Association of Australia for expert advice

on the Sydney/Illawarra water utility.

Mr Bruce Cole andMs PamO’Donoghue fromHunterWater

Corporation for expert advice on the Hunter water utility,

Mr Peter Littlejohns from the Sydney Catchment Authority

for expert advice on drought effects in Sydney catchments in

NSW.

We also thank Dr Nel Glass and Dr Stephen Kermode from

Southern Cross University, Ms Therese Dunn and Mr Paul

Houlder for their valuable contributions to this manuscript.

We wish to acknowledge the support from the Australian

Research Council Linage Grant (LP0348628) and the Network

for Spatially Integrated Social Science. This work is part of

a PhD thesis by Richard Summerhayes.

wat e r r e s e a r c h 4 5 ( 2 0 1 1 ) 5 7 1 5e5 7 2 6 5725

Appendix. Supplementary material

Supplementary data associated with this article can be found

in the online version, at doi:10.1016/j.watres.2011.08.045.

r e f e r e n c e s

APHA-AWWA-WEF, 1992. Standard Methods for the Examinationof Water and Waste Water, American Water WorksAssociation. Water Environment Federation, Washington DC.

APHA-AWWA-WPCF, 1998. Standard Methods for theExamination of Water and Waste Water, P. 1134, AmericanWater Works Association. Water Pollution Control Federation,Washington DC.

ABS, 2008. Year Book Australia, 2007. Australian Bureau ofStatistics (ABS), Australian Government Publishers, Canberra,Australia.

Bates, B.C., Kundzewicz, Z.W., Wu, S., Palutikof, J.P. (Eds.), 2008.Climate Change and Water. IPCC Secretariat, Geneva.

Bond, N.R., Lake, P.S., Arthington, A.H., 2008. The impacts ofdrought on freshwater ecosystems: an Australian perspective.Hydrobiologia 600, 3e16.

Bureau Of Meteorology, 2010. Climate Data Online. AustralianGovernment, Canberra. URL: http://www.bom.gov.au/climate/data/ (last accessed December 2010).

Bougeard, C.M.M., Goslan, E.H., Jefferson, B., Parsons, S.A., 2010.Comparison of the disinfection by-product formationpotential of treated waters exposed to chlorine andmonochloramine. Water Research 44, 729e740.

Centre for Epidemiology and Research, 2002. NSW Health Survey2002. NSW Department of Health, Sydney.

Charrois, J.W.A., Graham, D., Hrudey, S.E., Froese, K.L., 2004.Disinfection By-Products in small Alberta communitydrinking-water supplies. Journal of Toxicology andEnvironmental Health, Part A 67, 1797e1803.

Chen, C., Zhang, X.-J., Zhu, L.-X., Liu, J., He, W.-J., Han, H.-D., 2008.Disinfection by-products and their precursors in a watertreatment plant in North China: seasonal changes andfraction analysis. Science of the Total Environment 397 (1e3),140e147.

Chowdhury, S., Champagne, P., McLellan, P.J., 2009. Models forpredicting disinfection byproduct (DBP) formation in drinkingwaters: a chronological review. Science of the TotalEnvironment 407 (14), 4189e4206.

Cox, P., Fisher, I., Kastl, G., Jegatheesan, V., Warnecke, M.,Angles, M., Bustamante, H., Chiffings, T., Hawkins, P., 2003.Sydney 1998: lessons from a drinking water crisis. Journal ofthe American Water Works Association 95 (5), 147e161.

Dore, M.H.I., 2005. Climate change and changes in globalprecipitation patterns: what do we know? EnvironmentInternational 31 (8), 1167e1181.

Eikebrokk, B., Vogt, R.D., Liltved, H., 2004. NOM increase inNorthern European source waters: discussion of possiblecauses and impacts on coagulation/contact filtrationprocesses. Water Science and Water Technology: WaterSupply 44 (4), 47e54.

Galal-Gorchev, H., 1996. Chlorine in water disinfection. Pure andApplied Chemistry 68 (9), 1731e1736.

Garrido, S.E., Fonseca, M.G., 2010. Speciation and Kinetics oftrihalomethane formation in drinking water in Mexico.Ground Water Monitoring & Remediation 30 (1), 77e84.

Grellier, J., Bennett, J., Patelarou, E., Smith, R., Toledano, M.,Rushton, L., Briggs, D., Nieuwenhuijsen, M., 2010. Exposure todisinfection by-products and Adverse birth outcomes related

to Fetal Growth and Prematurity e A Systematic review andMeta-analysis. Epidemiology 21 (3), 300e313.

Hamilton, D.P., Schladow, G., Fisher, I.H., 1995. Controlling theindirect effects of flow diversions on water quality in anAustralian reservoir. Environment International 21 (5), 583e590.

Hoehn, R.C., Randall, C.W., 1979. Viruses, organics, and otherhealth-related Constituents of the Occoquan reservoir: Part Itrihalomethanes, Pesticides, and Metals. Criteria andStandards Div., USEPA, Washington D.C.

Hrudey, S.E., 2009. Chlorination disinfection by-products, publichealth risk tradeoffs andme.Water Research 43 (8), 2057e2092.

HWC, 2004. Hunter Water Catchment Report 2003/4. HunterWater Corporation (HWC), Newcastle Australia.

Hurst, A.M., Edwards, M.J., Chipps, M., Jefferson, B., Parsons, S.A.,2004. The impact of rainstorm events on coagulation andclarifier performance in potable water treatment. Science ofthe Total Environment 321 (1e3), 219e230.

Kampioti, A.A., Stephanou, E.G., 2002. The impact of bromide onthe formation of neutral and acidic disinfection by-products(DBPs) in Mediterranean chlorinated drinking water. WaterResearch 36 (10), 2596e2606.

Keegan, T., Whitaker, H., Nieuwenhuijsen, M.J., Toledano, M.B.,Elliott, P., et al., 2001. Use of routinely collected data ontrihalomethane in drinkingwater for epidemiological purposes.Occupational & Environmental Medicine 58 (7), 447e452.

Krasner, S.W., McGuire, M.J., Jacangelo, J.G., et al., 1989. Theoccurrence of disinfection by-products in US drinking water.Journal of American Water Works Association 81, 41e53.

Krasner, S.W., Sclimenti, M.J., Means, E.G., 1994. Qualitydegradation: implication for DBP formation. Journal ofAmerican Water Works Association 86 (6), 34e47.

McGuire, M.J., Meadow, R.G., 1988. AWWARF trihalomethanesurvey. Journal of AmericanWaterWorksAssociation 80, 61e68.

McGuire, M.J., McLain, J.L., Obolensky, A., 2002. InformationCollection Rule Data Analysis. AWWA Research Foundation,USA.

Murphy, B.F., Timbal, B., 2008. A review of recent climatevariability and climate change in southeastern Australia.International Journal of Climatology 28, 859e879.

National Cancer Institute, 1976. Report on the CarcinogenesisBioassayofChloroform.NationalCancer Institute,Bethesda,MD.

NHMRC, 2004. Australian Drinking Water Guidelines 6. NationalHealth & Medical Research Council. Australian Government,Canberra.

NHMRC, 2009. Draft Australian Drinking Water Guidelines.National Health & Medical Research Council (NHMRC),Canberra Australia.

NSW Department of Primary Industries, 2010. Drought. NSWDepartment of Primary Industries. NSW Government, Orange.URL: <http://www.dpi.nsw.gov.au/agriculture/emergency/drought/situation/drought-maps> (Last accessed December2010).

NSW Health, 2000. Drinking Water Monitoring Program. NSWHealth Department, pp. 1e39.

Richardson, S., 2005. New disinfection by-product issues:emerging DBPs and alternative routes of exposure. GlobalNEST Journal 7 (1), 43e60.

Richardson, S.D., Plewa, M.J., Wagner, E.D., Schoeny, R.,DeMarini, D.M., 2007. Occurrence, genotoxicity, andcarcinogenicity of regulated and emerging disinfection by-products in drinking water: a review and roadmap forresearch. Mutation Research 636, 178e242.

Rizzo, L., Selcuk, H., Nikolaou, A., Belgiorno, V., Bekbolet, M.,Meric, S., 2005. Formation of chlorinated organics in drinkingwater of Istanbul (Turkey) and Salerno (Italy). Global NESTJournal 7 (1), 95e105.

Rook, J.J., 1974. Formation of haloforms during chlorination ofnatural water. Water Treatment Exam 23, 234e243.

wat e r r e s e a r c h 4 5 ( 2 0 1 1 ) 5 7 1 5e5 7 2 65726

Simpson, K.L., Hayes, K.P., 1998. Drinking water disinfection by-products: an Australian perspective.Water Research 32,1522e1528.

Stein, P., 2000. The great Sydney water crisis of 1998. Water, Airand Soil Pollution 123, 419e436.

Soh, Y., Roddick, F., van Leeuwen, J., 2008. The future of water inAustralia: the potential effects of climate change and ozonedepletion on Australian water quality, quantity andtreatability. Environmentalist 28, 158e165.

SWC, 2002. Sydney Water Annual Report. Sydney WaterCorporation (SWC), Sydney, Australia.

USEPA, 1979. National Interim Primary Drinking WaterRegulations; Control of Trihalomethanes in Drinking Water.Environmental Protection Agency, U.S.

USEPA, 2008. Test Methods for Evaluating Solid Waste, Physical.Chemical Methods: SW-846. Environmental ProtectionAgency, U.S.

Whitaker, H., Nieuwenhuijsen, M.J., Best, N., Fawell, J., Gowers, A.,Elliot, P., 2003. Description of trihalomethane levels in three UKwater suppliers. Journal of Exposure Analysis andEnvironmental Epidemiology 13, 17e23.

Williams, D.T., LeBel, G.L., Benoit, F.M., 1995. A National Survey ofChlorinated Disinfection By-Products in Canadian DrinkingWater. Health Canada, Ottawa.

Williamson, C.E., Morris, D.P., Pace, M.L., Olson, O.G., 1999.Dissolved organic Carbon and Nutrients as Regulators of Lakeecosystems: resurrection of a more Integrated Paradigm.Limnology and Oceanography 44 (3), 795e803.