Roof-collected Rainwater Research Articles

DISSEMINATION OF DIARRHEAGENIC BACTERIA IN COMMUNITY-BASED NATURAL WATER SOURCES AND WASTEWATER ENVIRONMENTS: A COMPREHENSIVE ANALYSIS IN UNIVERSITY OF NIGERIA, NSUKKA AND ITS METROPOLIS.

The presence of pathogenic strains abounds in our environment, arising from many sources. The study was aimed at identifying Vibrio species, E. coli, and other coliforms in various water sources within a university setting and its metropolis. Approximately 20 samples from roof-collected rainwater, municipal piped tap water, borehole water and 60 samples of sewage effluent from the central effluent water of University of Nigeria, Nsukka were systematically collected at intervals and subjected to bacteriological analysis. The samples underwent dilutions, and aliquots were inoculated on chromocult and thiosulfate-citrate-bile salts-sucrose (TCBS) agar. Simultaneously, 100 ml of each natural water sample underwent membrane filtration, followed by the inoculation of TCBS agar plates in duplicates. Both sets of culture plates were incubated at 37 °C for 24 h. Further biochemical characterization was performed after microscopy. Susceptibility profile was done using disk diffusion assay. Descriptive statistics were used in the aggregation of the results where necessary. Results revealed that each sample, when plated on chromocult agar, yielded a substantial number of colonies of E. coli (bluish colour) and other coliforms (pink-red colonies). Notably, wastewater gave a maximum yield of Vibrio cholera. Conversely, all significant pathogenic Vibrio species were recovered on TCBS agar inoculated with natural water samples, wastewater and sewage effluent, with isolation rates appearing independent of both time (in weeks) and collection points. Antimicrobial susceptibility studies disclosed that some of the isolates exhibited antibiotic resistance. The study underscores the need to install appropriate measures to mitigate the contamination of the environment. Keywords: Wastewater, Vibrio, Antimicrobial, Chromocult, Pathogen, Sewage

Physicochemical and Microbiological Quality of Roof-harvested Rainwater in Urban Areas: A Review

This work proposes to consider the quality of roof-collected rainwater. There are three main stages. In the first stage, rainfall washes out the urban atmosphere with contaminants from aerosols and gases. The second stage refers to the catchment, where there is contamination due to the wash-off of particles settled on the roof’s surface roofing materials. The third stage refers to the first-flush, storage and plumbing system. In each stage, different processes take place and add specific contaminants to the initial precipitation. Only in the third stage, after the discard of the high-polluted initial rainwater, some physical processes (for example sedimentation and correction of pH) can also improve the quality of the rainwater harvest. This approach offers a clear view of the overall contamination processes that take place in a rainwater harvesting system.The most common microbiological and physicochemical contaminants that can be found in rainwater harvesting system were considered, together with the eventual presence of waterborne pathogens and emerging chemical contaminants, according to an extensive review of previous scientific works. Keywords: Rainwater, Physicochemical, Microbiological, Contaminants, waterborne DOI: 10.7176/JEES/12-10-05 Publication date: October 31 st 2022

Water Quality Assessment of Roof-collected Rainwater in Miri, Malaysia

Rainwater harvesting systems are becoming more acceptable as an alternative method to harvest water sources for both potable and non-potable uses. While the method has proven to be very simplistic and cost-effective, the collected rainwater source remains untreated and can pose serious health concerns if not used properly. This study focused on the physicochemical and heavy metal parameters of roof-collected rainwater in Miri, Sarawak. Individual sites were chosen throughout Miri, Sarawak for representative samples. Atomic Absorption Spectroscopy was used for the analysis of heavy metal concentrations. Heavy metal analysis included manganese, zinc, iron, copper, and cadmium. pH, temperature, turbidity, dissolved oxygen (DO), total suspended solids (TSS), total dissolved solids (TDS), nitrate, and fluoride were among the physicochemical parameters examined. Seasonal comparison indicated the majority of the higher concentration levels occurred during the wet season. The overall mean concentration for the physicochemical parameters indicated CLASS I usage, with the exception of BOD5, which was CLASS III usage. The overall mean concentration for metals analyzed indicated a CLASS I usage threshold with the exception of copper, which had concentrations well above the 0.02mg/L threshold for all sites. Thus, copper was considered one of the major contaminants for this study. Moreover, the types of storage tanks also showcased key findings. Open top storage tanks are more vulnerable to contamination than closed storage tanks. Metal storage tanks offer higher rainwater temperatures in comparison to other types of storage tanks.

Persistence of Escherichia coli O157:H12 and Escherichia coli K12 as Non-pathogenic Surrogates for O157:H7 on Lettuce Cultivars Irrigated With Secondary-Treated Wastewater and Roof-Collected Rain Water in the Field

Treated wastewater (TW) and roof-collected rain water (RW) that meet the required microbial quality as per Food Safety Modernization Act (FSMA) regulation may serve as alternative irrigation water sources to decrease the pressure on the current water scarcity. Alternative water sources may have different water characteristics that influence the survival and transfer of microorganisms to the irrigated produce. Further, these water sources may contain pathogenic bacteria such as Shiga-toxigenicEscherichia coli. To evaluate the risk associated with TW and RW irrigation on the fresh produce safety, the effect of TW and RW irrigation on the transfer of two non-pathogenicE. colistrains as surrogates forE. coliO157:H7 to different lettuce cultivars grown in the field was investigated. Lettuce cultivars “Annapolis,” “Celinet,” and “Coastline” were grown in the field at the Fulton farm (Chambersburg, PA). Approximately 10 days before harvest, lettuce plants were spray-irrigated with groundwater (GW), TW, or RW containing 6 log CFU ml−1of a mixture of nalidixic acid-resistantE. coliO157:H12 and chloramphenicol-resistantE. coliK12 in fecal slurry as non-pathogenic surrogates forE. coliO157:H7. On 0, 1, 3, 7, and 10 days post-irrigation, four replicate lettuce leaf samples (30 g per sample) from each group were collected and pummeled in 120 ml of buffered peptone water for 2 min, followed by spiral plating on MacConkey agars with antibiotics. Results showed that the recovery ofE. coliO157:H12 was significantly greater than the populations ofE. coliK12 recovered from the irrigated lettuce regardless of the water sources and the lettuce cultivars. The TW irrigation resulted in the lowest recovery of theE. colisurrogates on the lettuce compared to the populations of these bacteria recovered from the lettuce with RW and GW irrigation on day 0. The difference in leaf characteristics of lettuce cultivars significantly influenced the recovery of these surrogates on lettuce leaves. Populations ofE. coliO157:H12 recovered from the RW-irrigated “Annapolis” lettuce were significantly lower than the recovery of this bacterium from the “Celinet” and “Coastline” lettuce (P< 0.05). Overall, the recovery of specificE. colisurrogates from the RW and TW irrigated lettuce was comparable to the lettuce with the GW irrigation, where GW served as a baseline water source.E. coliO157:H12 could be a more suitable surrogate compared toE. coliK12 because it is an environmental watershed isolate. The findings of this study provide critical information in risk assessment evaluation of RW and TW irrigation on lettuce in Mid-Atlantic area.

Real-world sustainability analysis of an innovative decentralized water system with rainwater harvesting and wastewater reclamation

This study investigated an innovative decentralized water system which combined rainwater harvesting with wastewater reclamation to generate 39% of the water resources needed for a higher education institution with student and staff accommodation in India. We collected performance data to critically appraise the current water system, design alternatives and water management optimization opportunities. The campus was recently built in a hot, semi-arid region of India with a summer, monsoon and winter season. It represented in a microcosm the vision of leading Indian engineers for a more sustainable urban systems future. We collated the water infrastructure costs, blue and recycled water demands, chemical demands, electricity demands and operational costs over a calendar year. The annual institutional water demand was 379,768 m3, of which 32% was sourced from reclaimed wastewater, and 7% from roof-collected rainwater. Electricity consumption was 0.40 kWh/m3 for drinking water treatment, and 0.62 kWh/m3 for wastewater treatment, in line with median values reported for centralized systems. Rainwater harvesting and wastewater reclamation accounted for 42% of the water infrastructure costs, with a predicted payback period of >250 years through reduced operational costs. Scenario analysis recommended a water system design alternative with wastewater reclamation for ground maintenance only, which was predicted to yield similar environmental benefits, with an infrastructure cost payback period of only 15 years. Scenario analysis also revealed how better water management to address leakage, and more drought-tolerant landscaping, could improve environmental metrics of the current system by up to 52% and reduce operational costs by up to 23%. Reducing high domestic water usage was found to be essential to secure gains achieved with water infrastructure innovations. Rainwater harvesting had high infrastructure costs, and water policy in low- and middle-income countries should instead support wastewater reclamation and best practice in water management.

Pollutant treatment efficiencies through rainwater tank, recycled foamed glass and geofabrics

ABSTRACT This study investigated the effectiveness of removing pollutants from roof-collected rainwater through rainwater tank, filtration using recycled foam glass and geofabrics using series of laboratory experiments. It is found that rainwater tank itself helps to remove some pollutants, especially total suspended solids (TSS). To test the efficiency of recycled foam glass as filter material, the material was used to filter rainwater collected from roof. It is found that through such filtration most of the pollutants’ concentrations in the rainwater drop by about 50%. Also, removal efficiency of a 30 cm filter media is about double compared to a filter media of 10 cm height. However, concentrations of Suspended Solids, Copper and Lead in the filtered samples were higher than the concentrations in the raw sample, which might be due to leaching of pollutants from filter media as it is found that higher the filter depth, higher the pollutants concentrations in the filtrate. To overcome these pollutants’ leaching, similar experiments conducted with geotextile layer at the bottom of the filter material revealed that through the use of geotextile layer with 30 cm filter media, significant reductions of pollutants are achievable including an 87% removal in number of Faecal Coliforms.

Effect of cultivars and irrigation waters on persistence of indicator bacteria on lettuce grown in high tunnel

AbstractEffect of irrigation with groundwater (GW), primary‐treated wastewater (PTWW), secondary‐treated wastewater (STWW), and roof‐collected rainwater (RCR) on the microbial quality of lettuce cultivars “Annapolis,” “Celinet,” and “Coastline” grown in high tunnel was investigated. Lettuce plants were spray irrigated with irrigation waters once a week for 2 weeks and analyzed for indicator and pathogenic bacteria. PTWW irrigation resulted in the highest Escherichia coli recovery on the lettuce plants (4.7 log MPN/g) as compared to irrigation with other three waters on 0 day postirrigation (dpi). Lettuce cultivars affected the bacterial die‐off rate, where E. coli populations reduced the most by 1.5 log MPN/g on “Annapolis” lettuce on 2 dpi. The STWW and RCR irrigation did not significantly influence indicator bacterial populations on lettuce as compared to GW irrigation. The STWW and RCR containing low populations of indicator bacteria may be suitable for lettuce irrigation in Mid‐Atlantic area without affecting its microbial quality.

Lead exposure in an urban, free-ranging parrot: Investigating prevalence, effect and source attribution using stable isotope analysis

Anthropogenic lead use has resulted in widespread environmental lead contamination known to affect wildlife populations worldwide. Ecotoxicological investigations in wild birds have thus far prioritised waterfowl and raptor species and primarily addressed contamination in natural ecosystems. Urban areas are increasingly associated with high levels of heavy metal contamination, however the risk of lead exposure in urban wildlife is less well known. This study investigates lead exposure in an urban population of North Island Kaka (Nestor meridionalis septentrionalis), an endemic New Zealand parrot. The inquisitive nature of these birds, an expanding urban population and increased availability of food in the urban environment are the primary factors implicated in their dispersal into urban areas where there is increased exposure to anthropogenic sources of lead. Blood lead concentrations were assessed in free-ranging birds to quantify the prevalence and magnitude of lead exposure. The impact of lead on physiological and neurological function was assessed using behavioural and clinical examinations. Finally, lead stable isotope analysis was employed to investigate lead in roofing material as a potential source of exposure in the urban environment. Results indicate a significant prevalence of lead exposure in this population (43.2%) with a maximum recorded plasma concentration of 50.7μg/dL. Although no mortality was observed during this study, lead exposure was associated with reduced body condition in kaka. Behavioural changes were present in one individual with the highest recorded blood lead concentration. Lead isotope values of roof-collected rainwater overlapped with kaka blood lead isotope values, suggesting this to be an important source of exposure in this population. The prevalence of lead exposure observed in this study suggests that lead is a toxin of importance to kaka in this urban area. Wildlife intoxications largely result from anthropogenic lead sources and this study identifies a previously undescribed urban source of lead for wildlife.

Health Hazards Associated with Consumption of Roof-Collected Rainwater in Urban Areas in Emergency Situations.

The greater Wellington region, New Zealand, is highly vulnerable to large earthquakes because it is cut by active faults. Bulk water supply pipelines cross the Wellington Fault at several different locations, and there is considerable concern about severe disruption of the provision of reticulated water supplies to households and businesses in the aftermath of a large earthquake. A number of policy initiatives have been launched encouraging householders to install rainwater tanks to increase post-disaster resilience. However, little attention has been paid to potential health hazards associated with consumption of these supplies. To assess health hazards for householders in emergency situations, six 200-litre emergency water tanks were installed at properties across the Wellington region, with five tanks being allowed to fill with roof-collected rainwater and one tank being filled with municipal tapwater as a control. Such tanks are predominantly set aside for water storage and, once filled, feature limited drawdown and recharge. Sampling from these tanks was carried out fortnightly for one year, and samples were analysed for E. coli, pH, conductivity, a range of major and trace elements, and organic compounds, enabling an assessment of the evolution of water chemistry in water storage tanks over time. Key findings were that the overall rate of E. coli detections in the rain-fed tanks was 17.7%, which is low in relation to other studies. We propose that low incidences of may be due to biocidal effects of high zinc concentrations in tanks, originating from unpainted galvanised steel roof cladding. Lead concentrations were high compared to other studies, with 69% of rain-fed tank samples exceeding the World Health Organisation’s health-based guideline of 0.01 mg/L. Further work is required to determine risks of short-term consumption of this water in emergency situations.

A review on physicochemical and microbiological contamination of roof-harvested rainwater in urban areas

Abstract This work proposes to consider the quality of roof-collected rainwater as the sum of three main stages. In the first one, rainfall washes out the urban atmosphere and scavenges contaminants from aerosols, gases and thin volatile particles. The second stage refers to the catchment, in which occurs contamination due to the wash-off of particles settled on the roof’s surface as well as the scavenging of roofing materials. The third stage refers to the first-flush, storage and plumbing system. In each stage, different processes take place and add specific contaminants to the initial precipitation. Only in the third stage, after the discard of the high-polluted initial rainwater, some physical processes (sedimentation and pH increase) can also improve the quality of the rainwater harvest. With this approach, it is offered a clear view of the overall contamination processes that take place in a rainwater harvesting system. The most common microbiological and physicochemical contaminants that can be found in rainwater harvesting system were regarded, together with the eventual presence of waterborne pathogens and emerging chemical contaminants, according to an extensive review of 172 previous scientific and technical works.

Demographics, practices and water quality from domestic potable rainwater harvesting systems

In semi-arid regions experiencing rapid population growth, rainwater harvesting is becoming increasingly important. Roof-collected rainwater is the exclusive water source for many households worldwide. Improper collection, storage or treatment of rainwater can result in adverse health effects. This study surveys rainwater harvesting practices and examines water quality from these systems. At 36 households, stored ‘pre-filtration’ rainwater and ‘post-filtration’ water from the kitchen faucet used for drinking and cooking were sampled. Rainwater harvesters desire to conserve water and believe that rainwater is more healthful than surface or groundwater. Almost 95% of homeowners use filtration and purification devices, but 64% have never tested their water. Coliform bacteria were not found in any post-filtration water, but some pre-filtration water samples were high in total heterotrophic bacteria. Lead levels exceeded the United States Environmental Protection Agency (USEPA) standard of 15 μg L−–1 in 25% of pre-filtration samples and 6% of post-filtration samples. First-flush diversion devices significantly decreased the likelihood of pre-filtration lead levels above 15 μg L−1. Aluminium, copper and iron exceeded USEPA recommended levels in a small percentage of homes. Although water from roof-collected rainwater harvesting systems was generally within drinking water standards, regular testing should be encouraged to avoid potential health problems.

Monitoring of water quality from roof runoff: Interpretation using multivariate analysis

The quality of harvested rainwater used for toilet flushing in a private house in the south-west of France was assessed over a one-year period. Temperature, pH, conductivity, colour, turbidity, anions, cations, alkalinity, total hardness and total organic carbon were screened using standard analytical techniques. Total flora at 22 °C and 36 °C, total coliforms, Escherichia coli and enterococci were analysed. Overall, the collected rainwater had good physicochemical quality but did not meet the requirements for drinking water. The stored rainwater is characterised by low conductivity, hardness and alkalinity compared to mains water. Three widely used bacterial indicators - total coliforms, E. coli and enterococci - were detected in the majority of samples, indicating microbiological contamination of the water. To elucidate factors affecting the rainwater composition, principal component analysis and cluster analysis were applied to the complete data set of 50 observations. Chemical and microbiological parameters fluctuated during the course of the study, with the highest levels of microbiological contamination observed in roof runoffs collected during the summer. E. coli and enterococci occurred simultaneously, and their presence was linked to precipitation. Runoff quality is also unpredictable because it is sensitive to the weather. Cluster analysis differentiated three clusters: ionic composition, parameters linked with the microbiological load and indicators of faecal contamination. In future surveys, parameters from these three groups will be simultaneously monitored to more accurately characterise roof-collected rainwater.

Rainwater harvesting: quality assessment and utilization in The Netherlands

The use of roof-collected rainwater as a freely available and sustainable alternative to drinking water produced by drinking water companies increases worldwide. Initially, rainwater is free of microbial contamination, but it may become contaminated by animals and humans or, alternatively, human pathogens may grow in stored rainwater resulting in a significant human health risk from infectious diseases. This three-year study demonstrated that rainwater stored in different reservoirs in The Netherlands was frequently faecally contaminated and incidentally contained potential human pathogens such as Campylobacter, Cryptosporidium, Giardia, Aeromonas hydrophila and Legionella. Analysis of samples during a period with variable weather conditions showed a correlation between rainfall intensity and faecal indicator counts and increased detection of pathogens after heavy rainfall incidents. Outside temperature had a limited effect on both the temperature and the microbiological quality of the water in the reservoirs, which did not comply with Dutch drinking water legislation and should thus not be consumed without treatment. In general, a health risk may arise from exposure to pathogens when contaminated droplets are inhaled, ingested or come into contact with the skin. Health risks may be reduced by regular cleaning of the collection, storage and transport means, but to assess their efficacy field intervention studies are required.

Pathogens in urban wastewaters suitable for reuse

Urban wastewaters, including domestic wastewater, grey water and roof-collected rain water, are all potential sources of water, which can be reused in an effort to conserve limited water resources. Urban wastewaters may contain a range of pathogenic microorganisms, which are of concern for water reuse due to the potential for pathogen transmission from reuse applications. In particular, regardless of the source, grey water is shown to consistently contain bacteria of faecal origin. Most potentially harmful species occur at relatively low concentration such that only those with low infectious doses are likely to be of real concern. Example species include Campylobacter jejuni, shiga toxin producing Escherichia coli and Shigella spp.

Potential Use of Monsoon Rainwater for Drinking Purpose in Bangladesh

This study investigates the feasibility of the utilization of monsoon rainwater for domestic purpose in Bangladesh. A survey was done in Rajshahi city in Bangladesh about the prospect and possibilities of rainwater harvesting (RWH). RWH system was not found in any individual or commercial apartment in the city. But, however, in rainy season, women about 46% houses used to collect rainwater from their roofs for domestic uses at least once in a year. In this study, a numbers of rainwater samples were collected from open atmosphere and through two different roof catchments (galvanized iron and concrete) and analysed the physico-chemical quality. pH of all the samples ranges from 6.3 to 7.7. The results showed the physico-chemical quality of the samples were found within the limits of WHO's standard of drinking water except the particulate matter in rainwater. The study recommend that the rainwater would be allowed to stand for 6-10 hours to settle more than 90% of the particulate matter and a 3-4 folds fine thin clothes could be used as filter to remove almost all particulate matter from the water. Moreover, the study observed that the microbial treatment technologies such as chlorination, solar or UV radiations would be technically feasible and economically sound to destroy micrograms in stored rainwater. Further research is imperative on potential indicators of both microbiological quality and health risk to minimize contamination of roof-collected rainwater.

An Assessment of the Presence of Escherichia coli in the roof-collected rainwater from some areas around Nairobi.

One of the sources of feacal contamination of rainwater harvested from roofs is wind-blown dust containing particulate matter from animal faeces, or through direct defecation. Since the primary habitat for Escherichia coli (E.coli) is the gastro-intestinal tract of mammals and birds (Atlas 1984), it\'s a good indictor of feacal contamination (Hazen, 1988). This study aimed to investigate the presence of E.coli. In rainwater samples collected from roofs in some areas around Nairobi, which have different levels of livestock density. Forty four of the 89 samples collected tested positive for the presence of E.coli from Ngong Division, which had a cattle density of 1446 per square Kilometre was, 55%, but it was not significantly different from both Kikuyu Division: cattle density of 166; both of which had 34% of the samples testing positive to E.coli (p=0.3094). It was concluded that rain water harvested from roofs for human consumption in the study area should be treated before use. The Kenya Veterinarian Vol. 27 2004: pp. 97-102

A Legionnaires’ disease outbreak: A water blaster and roof-collected rainwater systems

In February 2006, an outbreak of Legionnaires’ disease (LD) was identified in Beachlands, a small, isolated east Auckland suburb. It was investigated through case finding, a case–control study, sampling potential sources of infection and by molecular typing (using sequence-based typing (SBT) of all Legionella pneumophila serogroup 1 (Lp1) isolates). Lp1 was isolated from the respiratory tract of one case, the roof-collected rainwater systems of five households (three associated with cases) and from a water blaster at a nearby marina. All isolates were indistinguishable, exhibiting the same SBT allele pattern. Three LD cases lived within 500 m of the water blaster (the fourth case within 1250 m) and downwind in prevailing conditions. Another domestic roof-collected rainwater supply contaminated by Lp1 (identical SBT pattern) was incidentally identified in another suburb 4 km east of Beachlands. This is the first outbreak of LD linked to roof-collected rainwater supplies and the first isolation of Legionella from these systems in New Zealand. Aerosols containing Legionella discharged to air by the marina water blaster may have infected some cases directly or may have seeded roof-collected rainwater systems. Some cases may have been exposed by contaminated bathroom showers. Roof-collected rainwater systems need appropriate design, careful cleaning and the maintenance of hot water temperatures at a minimum of 60 °C to reduce the chances of Legionella multiplying. Further research into the ecology of Legionella in roof-collected rain water systems is indicated.

Water quality of rooftop rainwater harvesting systems: a review

There has been a growing interest, especially in developing countries, in rooftop rainwater harvesting as an alternative source of drinking water. This paper reviews the available information on the water quality of rooftop rainwater harvesting systems. Various factors that affect the physico-chemical and microbiological quality of harvested water are discussed. Different contaminants including heavy metals and trace organic pollutants in the roof runoff reported from different parts of the world are compared. The review shows that the quality of harvested water from roof catchments often does not meet the drinking-water guideline values. Most of the studies reveal that harvested water is heavily contaminated microbiologically by a variety of indicator and pathogenic organisms unless special care is taken during collection and storage of rainwater. Heavy metals and trace organics could also pose problems in some cases. The review thus indicates that the purity of rainwater harvested from rooftops should not be taken for granted, and analysis of the harvested water especially for microbiological contamination should be undertaken. Appropriate treatment of collected rainwater would be necessary to make the harvested rainwater fit for drinking. The review also shows the need for further research on proper design and maintenance strategies to minimise contamination of roof-collected rainwater supplies.

First incursion of Salmonella enterica serotype typhimurium DT160 into New Zealand.

An outbreak of human Salmonella enterica serotype Typhimurium DT160 infection in New Zealand was investigated from May to August 2001. Handling of dead wild birds, contact with persons with diarrheal illness, and consumption of fast food were associated with infection. Contaminated roof-collected rainwater was also detected.

Contamination of potable roof-collected rainwater in Auckland, New Zealand

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 <1 FC/100 mL. Eighteen supplies (14.4%) exceeded the NZDWS MAV for lead of 0.01 mg/L and three (2.4%) exceeded that for copper, of 2 mg/L. Those supplies with lead or galvanised iron comprising part of the roof or collecting system were more likely to show lead contamination ( p=0.019) as were those supplies with a pH less than 7 ( p=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% CI 1.15–9.01, 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: ≥30 FC or ≥60 ENT). Cryptosporidium oocysts were detected in 2 (4%) of these. 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.