Wat. Res. Vol. 35, No. 6, pp. 1518–1524, 2001 # 2001 Elsevier Science Ltd. All rights reserved Printed in Great Britain 0043-1354/01/$-see front matter PII: S0043-1354(00)00420-6 CONTAMINATION OF POTABLE ROOF-COLLECTED RAINWATER IN AUCKLAND, NEW ZEALAND GREG SIMMONS 1 *, VIRGINIA HOPE 1,2 , GILLIAN LEWIS 3 , JOHN WHITMORE 1 and WANZHEN GAO 1 1 Auckland Healthcare Public Health Protection, Private Bag 92 605, Symonds St, Auckland, New Zealand; 2 National Environmental and Occupational Health Research Unit, Faculty of Medicine and Health Sciences, University of Auckland, New Zealand and 3 School of Biological Sciences, University of Auckland, New Zealand (First received 21 December 1999; accepted in revised form 27 July 2000) Abstract}One-hundred and twenty-five domestic roof-collected rainwater supplies in four rural Auckland districts were investigated in a cross-sectional survey to determine water quality. Samples of cold faucet water were analysed for physico-chemical and microbiological determinands, including metals (zinc, copper and lead), bacterial indicator organisms}heterotrophic plate count (HPC), total coilforms (TC), faecal coliforms (FC), enterococci (ENT), bacterial pathogens including Salmonella spp., Legionella spp., Campylobacter spp., Aeromonas spp. and the protozoa, Cryptosporidium and Giardia. Twenty-two supplies (17.6%) exceeded one or more of the maximum acceptable values (MAV) or maximum guideline values for chemical determinands of the New Zealand Drinking Water Standards (NZDWS) and 70 (56.0%) supplies exceeded the microbiological criteria of 51FC/100mL. Eighteen supplies (14.4%) exceeded the NZDWSMAVforleadof0.01mg/Landthree(2.4%)exceededthatforcopper,of2mg/L.Thosesupplies with lead or galvanised iron comprising part of the roof or collecting system were more likely to show lead contamination ( p ¼ 0:019) as were those supplies with a pH less than 7 ( p ¼ 0:013). The presence of the indicator organisms HPC, TC, FC and ENT were all significantly correlated with one another. Aeromonas spp. were identified in 20 (16.0%) supplies. There was a positive association between the presence of Aeromonas and the bacterial indicator organisms. Households reporting at least one member with gastrointestinal symptoms in the month prior to sampling, were more likely to have Aeromonas spp. identified in their water supply than those households without symptoms (odds ratio 3.22, 95% CI1.15– 9.01, p=0.021). Salmonella typhimurium was detected in one of 115 (0.9%) supplies. Legionella spp. and Campylobacter spp. were not detected. There were 50 supplies sampled for protozoa (sampling criteria: 30FCor 60 ENT). Cryptosporidium oocystsweredetectedin2(4%)ofthese. Giardia was not detected. This study demonstrates that roof-collected rainwater systems provide potable supplies of relatively poor physicochemical and microbiological quality in the Auckland area. Further research is required on Aeromonas spp. as potential indicators of both microbiological quality and health risk along with design and maintenance strategies to minimise contamination of potable roof-collected rainwater supplies. # 2001 Elsevier Science Ltd. All rights reserved Key words}rainwater quality, potable, contamination, microbiological, physicochemical, health INTRODUCTION Roof-collected rainwater is generally accepted to be a safe and abundant source for potable domestic supply in New Zealand and is frequently the only available domestic water source in rural households. The safety of this water source is of concern as contamination of domestic rainwater systems has been linked to a number of instances of human infection (Brodribb et al., 1995; Murrell and Stewart, 1983) and chemical intoxication (Body, 1986). A number of studies have investigated the prevalence of microbiological (Lye, 1987; Fujioka and Chinn, 1987; Fujioka et al., 1991; Habler and Waller, 1987; Waller et al., 1984) and chemical (Gumbs and Dierberg, 1984; Olem and Berthouex, 1989; Sharpe and Young, 1982; Young and Sharpe, 1984) con- taminants in roof-collected rainwater. These studies have largely consisted of cross-sectional surveys of non-randomly selected households with relatively small sample sizes (8–83 households). Direct compar- ison between studies is difficult because of variation in the design, sampling and analytical methods. Nevertheless, where samples were taken at tap for faecal coliform (FC) analysis, between 3.3 and 80% of supplies in these surveys had 1FC/100mL. Copper and lead (Gumbs and Dierberg, 1984; Young and Sharpe, 1984) have been found in tap water at *Author to whom all correspondence should be addressed. Tel.: +64-9-623-4613; fax: +64-9-630-7431; e-mail: gregs@ahsl.co.nz 1518