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: > or = 30 FC or > 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 physiochemical 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.     

Impact of inland pollution sources on the bacteriological water quality of the Southern Ganghwado Bay Area,South Korea

The bacteriological pollution of water is a serious global environmental issue. The pollution of water by human and animal wastes can be a source of hazardous pathogens, which may pose serious health risks. In this study, we evaluated the microbiological water quality in the southern Ganghwado Bay area, South Korea. A total of 30 samples (14 discharge water samples from the drainage area and 16 sea water samples from the adjacent area) were analyzed for the concentrations of total coliforms (TC) and fecal coliforms (FC) in November 2013. The highest concentration of FC (28,000 MPN/100 mL) was found at site L1 (inland). The highest mean concentrations of coliforms were found at sites W9 (sea water) and W11 (sea water), with TC and FC concentrations of 33 MPN/100 mL. In conclusion, site L1 located near W9 and W11 is clearly identified as the main source of pollution at Dongmak Beach.     

Microbiological surveillance of private water supplies in England - The impact of environmental and climate factors on water quality

A passive surveillance system captured information on 34,904 microbiological samples from 11,233 private drinking water supplies within England as well as the associated constructional, climatic and environmental variables. Escherichia coli was detected in 6588 (18.87%) of samples and at least one positive sample was detected from 3638 (32.39%) of sites. However, this estimate of supplies failing to meet the European drinking water E. coli standard was probably an underestimate as the more samples taken per supply, the more likely the supply was to fail. A multivariable model of private water supplies data showed a strong seasonal impact, with samples between January and May being significantly less contaminated with E. coli than samples between June and December. Samples from springs (OR 2.5, CI 2.0-3.1) or surface waters (OR 2.4, CI 0.8-7.0) were more likely to fail than groundwater sources, as were supplies with no effective treatment (OR1.8, CI 1.5-2.3). Commercial supplies were less likely to fail than domestic supplies (OR 0.63, CI 0.48-0.83) and the probability of failure was linearly associated with the density of sheep in the area and rainfall on the previous day. A Monte Carlo modelling approach was used to estimate that, had sufficient samples been taken, 54% (95% confidence intervals 49-59%) of all private water supplies in England were likely to be unsatisfactory. These findings will be able to inform risk assessments of private water supplies prior to microbiological results being available.     

Comparing microbial water quality in an intermittent and continuous piped water supply

Supplying piped water intermittently is a common practice throughout the world that increases the risk of microbial contamination through multiple mechanisms. Converting an intermittent supply to a continuous supply has the potential to improve the quality of water delivered to consumers. To understand the effects of this upgrade on water quality, we tested samples from reservoirs, consumer taps, and drinking water provided by households (e.g. from storage containers) from an intermittent and continuous supply in Hubli–Dharwad, India, over one year. Water samples were tested for total coliform, Escherichia coli, turbidity, free chlorine, and combined chlorine. While water quality was similar at service reservoirs supplying the continuous and intermittent sections of the network, indicator bacteria were detected more frequently and at higher concentrations in samples from taps supplied intermittently compared to those supplied continuously (p < 0.01). Detection of E. coli was rare in continuous supply, with 0.7% of tap samples positive compared to 31.7% of intermittent water supply tap samples positive for E. coli. In samples from both continuously and intermittently supplied taps, higher concentrations of total coliform were measured after rainfall events. While source water quality declined slightly during the rainy season, only tap water from intermittent supply had significantly more indicator bacteria throughout the rainy season compared to the dry season. Drinking water samples provided by households in both continuous and intermittent supplies had higher concentrations of indicator bacteria than samples collected directly from taps. Most households with continuous supply continued to store water for drinking, resulting in re-contamination, which may reduce the benefits to water quality of converting to continuous supply.     

The Microbiological Quality of Private Water Supplies

This paper provides a detailed assessment of the microbiological quality of a selection of private water supplies. Samples were taken from 91 supplies and analyzed for total coliforms, faecal coliforms and faecal streptococci. The microbiological quality of the samples was generally poor, with almost 50% of the supplies failing to meet the required standards on at least one occasion. Given the high level of sanitary microbiological failures, there is the possibility that harmful microorganisms could be present and a significant risk to health cannot be discounted.     

The Microbiological Quality of Private Water Supplies

This paper provides a detailed assessment of the microbiological quality of a selection of private water supplies. Samples were taken from 91 supplies and analyzed for total coliforms, faecal coliforms and faecal streptococci. The microbiological quality of the samples was generally poor, with almost 50% of the supplies failing to meet the required standards on at least one occasion. Given the high level of sanitary microbiological failures, there is the possibility that harmful microorganisms could be present and a significant risk to health cannot be discounted.     

Risk factors contributing to microbiological contamination of shallow groundwater in Kampala,Uganda

A study of water quality variation in shallow protected springs in Kampala was undertaken over a 12-month period to assess the causes of microbiological contamination. The microbiological quality of water was assessed using thermotolerant coliforms and faecal streptococci. Sanitary inspections and hazard assessments were undertaken to identify faecal sources (hazards), contaminant pathways and contributory factors. Data were collected on rainfall and population as additional factors potentially exerting an influence on microbiological quality. Initial analysis of the data showed a significant relationship between median level of contamination and rainfall, in particular to short-term rainfall events. Total sanitary risk score showed a significant relationship with median level of contamination, but population density may be a confounding factor. The raw microbiological data were transformed into five water quality targets: <1 and < or =10 cfu 100ml(-1) for faecal streptococci; and <1, < or =10 and < or=50 cfu 100 ml(-1) for thermotolerant coliforms. The presence of individual risk factors as well as variables for rainfall and population density were analysed with respect to failure to meet these water quality targets using contingency tables. Logistic regression models were developed for each of the five water quality targets. The analysis strongly suggested that there is rapid recharge of the springs after rainfall and this leads to microbiological contamination. On-site sanitation was less important than other sources of faecal matter, which was consistent with a low sanitation coverage in the study area. The study suggested that improving sanitary completion and local environmental hygiene was more important than controlling on-site sanitation in improving the quality of these springs.     

Bacterial quality of tile drainage water from manured and fertilized cropland

Bacterial contamination of tile drainage water in three manured and one non-manured cropped fields was studied over a 4-year period at a large, mixed farm near Ottawa, Ontario, Canada. Concentrations of total coliforms, fecal coliforms (FC), fecal streptococci (FS) and Standard Plate Counts at 20 and 35°C, in both the drainage water and the applied dairy cattle liquid manure varied over a wide range. Bacterial concentrations in long-term winter-stored manure were much lower than in relatively fresh manure. Concentrations of FC and FS in the drainage water from the manured fields were lower than concentrations in the applied manure by 3–5 orders of magnitude. Bacterial concentrations in drainage water from all fields had low geometric mean and median values for all parameters tested. Water quality was satisfactory most of the time for recreational use or for use as a raw water source for drinking water supplies. Factors such as precipitation appeared to have a greater influence on drainage water quality than manure application. Influence of soil type on bacterial concentrations in drainage water from the manured fields was not evident. However, a lower unit-area tile outflow in coarse-textured soil compared to fine-textured soil indicated a greater potential in the former for fecal bacteria reaching groundwater beneath the tile drains.     

Escherichia coli O157:H7 in drinking water from private water supplies in the Netherlands

The microbiological quality of drinking water from 144 private water supplies in the Netherlands was tested and additionally the occurrence of Escherichia coli O157 was examined. Faecal indicators were enumerated by using standard membrane filtration methods. The presence of E. coli O157 was determined using a specific enrichment method. Eleven percent of the samples contained faecal indicators whereas E. coli O157:H7 was isolated from 2.7% of the samples that otherwise met the drinking water standards. The E. coli O157 positive water supplies were located on camp-sites in agricultural areas with large grazer densities. Pulsed field gel electrophoresis (PFGE) analysis suggested that cattle might have been the cause of contamination. Our results indicate that compliance with microbiological quality standards obtained in routine monitoring does not always guarantee the absence of pathogens. The presence of pathogens such as E. coli O157 may suggest possible health consequences; however, a risk assessment process should be performed as the monitoring of both faecal indicator parameters and pathogens do not predict the effect of microbial contamination of drinking water on a population.     

Disinfection observations on a major unfiltered water supply in Scotland

The Loch Katrine water supply to Glasgow was unfiltered until a new treatment works was completed in 2007. Disinfection observations on the unfiltered supply are reported here for the decade 1995–2004. On one half of the supply, raw water contamination by gulls led to annual final water microbiological failure rates up to 2.7%, which fell below 0.4% after introducing revised gull control measures. Seasonality in gull contamination contributed to marked seasonality in observed final water microbiological failure rates. A 14‐min chlorine contact time at pH 5.8 realised all the effective disinfection; a longer second stage contact time at pH 8.6 provided no significant (P > 0.05) improvement. For a range of raw water Escherichia coli counts, a logistic regression model predicted probabilities of a final water E. coli failure that varied with quarterly period; this was consistent with seasonal factors, aside from raw water quality, contributing to probability of these failures.     

Comparison of total coliform,fecal coliform,and enterococcus bacterial indicator response for ocean recreational water quality testing

In July 1999, California's ocean recreational bacterial water quality standards were changed from a total coliform (TC) test to a standard requiring testing for all three bacterial indicators: TC, fecal coliforms (FC), and enterococci (EC). To compare the relationship between the bacterial indicators, and the effect that changing the standards would have on recreational water regulatory actions, three regional studies were conducted along the southern California shoreline from Santa Barbara to San Diego, California. Two studies were conducted during dry weather and one following a large storm event. In each study, samples were collected at over 200 sites which were selected using a stratified random design, with strata consisting of open beach areas and rocky shoreline, and areas near freshwater outlets that drain land-based runoff. During the dry weather studies, samples were collected once per week for 5 weeks. For the storm event study, sampling occurred on a single day about 24 h following the storm. The three indicator bacteria were measured at each site and the results were compared to the single sample standards (TC > 10,000; FC > 400 and EC > 104 MPN or cfu/100 ml). EC was the indicator that failed the single sample standards most often. During the wet weather study, 99% of all standard failures were detected using EC, compared with only 56% for FC, and 40% for TC. During the Summer Study, EC was again the indicator that failed the single sample standards most often, with 60% of the failures for EC alone. The increased failure of the EC standard occurred consistently regardless of whether the sample was collected at a beach or rocky shoreline site, or at a site near a freshwater outlet. Agreement among indicators was better during wet weather than during dry weather. During dry weather, agreement among indicators was better near freshwater outlets than along open shoreline. Cumulatively, our results suggest that replacement of a TC standard with an EC standard will lead to a five-fold increase in failures during dry weather and a doubling of failures during wet weather. Replacing a TC standard with one based on all three indicators will lead to an eight-fold increase in failures. Changes in the requirements for water quality testing have strong implications for increases in beach closures and restrictions.     

Microbiological quality of water from hand-dug wells used for domestic purposes in urban communities in Kumasi,Ghana

Assessment was done on the microbiological quality of water in hand-dug wells in urban communities in Kumasi, Ghana. A total of 256 water samples were taken from eight wells and examined for faecal coliforms, enterococci and helminths. High contamination levels were recorded in the wells, more so in the wet season, with faecal coliforms levels between 6.44 and 10.19 log units and faecal enterococci between 4.23 and 4.85 CFU per 100 ml. Influence on protection and lining of wells on water quality was not pronounced but mechanization reduced contamination significantly by about 3 log units. This study shows a stronger influence of poor sanitation and improper placement of wells on water quality compared to improvements made from lining and protection of wells. In the race to increase access to drinking water in poor urban settlements, quality of groundwater could be a major barrier, if provision of drinking water is not matched with improvements in sanitation and urban planning.     

Pathogenic or potentially pathogenic bacteria as contaminants of fresh water from different sources in Araraquara, Brazil

The microbiological quality of various fresh waters in the Araraquara region, state of São Paulo, Brazil was investigated. Ninety-nine water samples were taken from rivers, reservoirs, artesian and non-artesian wells, springs and tap waters, and these waters were analysed using: plate counts of heterotrophic microorganisms (per 1 ml); Most Probable Number (MPN) of fecal coliforms and E. coli (per 100 ml); tests for presence of Salmonella, Shigella, Yersinia, the E. coli pathogens of classes EPEC, ETEC and EIEC and Mycobacterium, Shigella, Yersinia and enteroinvasive E. coli (EIEC) were not isolated. The other types of microorganisms were isolated in varying proportions. We conclude that the waters investigated represent a potential microbiological health risk.     

Microbiological water quality in urban coastal beaches: the influence of water dynamics and optimization of the sampling strategy

In the summer 2001, the microbiological water quality of two contiguous urban coastal beaches (Porto, Portugal) was surveyed for 18 consecutive days. The sampling strategy consisted in sampling surface water in early morning, noon and afternoon. A total of 184 samples were processed at Pastoras beach, a confined area between two jetties, and Ourigo Beach more open to the ocean. At the first beach site, all samples exceeded fecal contamination above guide values (GV) and 82.6% above mandatory values (MV) set out in the EU Bathing Water Directive; whereas at Pastoras Beach, the figures were 93.5% for GV and 26.1% for MV, showing a potential health risk. The periodicity of fecal indicators in raw sewage, the tidal status and wind conditions dramatically influenced the water quality. The quality decreased in the morning regardless of tide conditions, but improved subsequently during the day, particularly during high tide and under the influence of afternoon NW winds. These dynamics are incompatible with the fortnight routine sampling according to the recommendations of the EU Bathing Water Directive, and the strategy should be revised on a beach-to-beach basis, having in mind the profile for the coastal zone.     

Seasonal Variations in the Quality of Spring Waters Used as Private Supplies

The quality of water issuing from four springs which act as private water supplies was monitored regularly over a twelve-month period. Bacteriological analyses for faecal coliforms and chemical analyses for iron, manganese, aluminium and lead were carried out and related to meteorological conditions. Bacteriological quality, which was influenced by the amount and duration of rainfall, deteriorated rapidly after heavy rain and improved markedly during dry periods. Chemical quality was a function of both the rainfall and atmospheric pollution emanating from the nearby urban conurbation. The results are discussed with relation to the statutory requirements for local authorities to monitor small private water supplies.     

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.     

Performance of a sub-surface flow constructed wetland in polishing pre-treated wastewater-a tropical case study

This paper reports on the performance of three units of a sub-surface horizontal flow constructed wetland (CW) pilot plant in polishing effluent from the upflow anaerobic sludge blanket (UASB) reactor plant. Studies on the use of UASB for on-site wastewater pre-treatment were initiated in Tanzania for the first time in 1993, while initial research works on the application of CW for polishing effluent from UASB, the results of which are reported in this paper began in 1999. In this study the UASB reactor plant received and pre-treated part of the wastewater from the student's hostels at the University College of Lands and Architectural Studies in Tanzania. Out of the three units, unit B was planted with Phragmites mauritianus, unit C with Typha latifolia and A was used as a control. Both P.mauritianus and T.latifolia have been extensively researched in Europe and USA as suitable species of vegetation in CW. However, very limited studies on the suitability of these wetland plants have been reported under tropical climate. The studied parameters were chemical oxygen demand (COD), nitrate (NO(3)-N), nitrite (NO(2)-N), ammonium (NH(4)-N), faecal coliforms (FC), total coliforms (TC), pH, temperature and dissolved oxygen (DO). The study was carried out at an average hydraulic retention time of 1.93 days (1.85 in unit A, 1.96 in unit B and 1.99 in unit C) obtained as a ratio of the volume of wastewater in the wetland and the volumetric flow rate of wastewater through the wetland unit while taking into consideration the porosity of the media. Better performance for the vegetated units B and C were obtained compared to the control unit A. Nutrients were least removed in all units (NH(4)-N 11.2%, 25.2% and 23% in units A, B and C, respectively, NO(3)-N 32.2%, 40.3% and 44.3% for units A, B and C, respectively, and NO(2)-N 23.9%, 38.5% and 23.1% for units A, B and C, respectively). The COD removal rate was 33.6%, 56.3% and 60.7% for units A, B and C, respectively. The study also indicated that pH increased from the influent to the effluent and that DO increase was related to the decrease of temperature. FC and TC removal ranged from 43% to 72%, with the least removal in unit A.     

Evaluation of microbiological accumulation capability of the commercial sponge Spongia officinalis var. adriatica (Schmidt) (Porifera, Demospongiae)

This study was carried out to evaluate the microbiological accumulation capability of the demosponge Spongia officinalis var. adriatica. Six microbiological parameters were researched in two sampling periods in the water and in reared sponge samples coming from sites with different degrees of microbial contamination: an off-shore fish farm displaced off the Apulian coast (Southern Adriatic Sea) and a no-impacted area displaced into the Marine Protected Area of Porto Cesareo (Apulian coast-Ionian Sea). We detected the density of culturable heterotrophic bacteria by spread plate on marine agar, total culturable bacteria at 37 degrees C on Plate Count Agar and vibrios on thiosulphate-citrate-bile-sucrose-salt (TCBS) agar. Total and fecal coliforms as well as fecal streptococci concentrations were detected by the MPN method. Bacterial densities were always higher in the sponge homogenates compared with the corresponding seawater in the sampling points and in both sampling periods. As regard vibrios, total culturable bacteria at 37 degrees C and fecal streptococci concentrations, the highest values were observed in the sponge samples coming from the off-shore fish farm during the summer period. The ability of Spongia officinalis var. adriatica to accumulate the microbial pollution indicators suggests that this species can be employed as a bioindicator for monitoring water quality.     

Trace inorganics in rural potable water and their correlation to possible sources

Ninety-eight water samples, comprising about 10% of the total sources available to rural homes in Hampton County, South Carolina, were randomly selected and analyzed for inorganic constituents. Chemical contamination is widespread in this area and many people are using substandard quality water.A noticeable number of water samples showed unacceptable levels of arsenic, iron, manganese and mercury. Iron and collodial material were chiefly responsible for turbidity in 19% of the water sources. Acceptable levels of cadmium, chloride, copper, lead, nitrate, phosphate, sodium, total solids and zinc were detected in most of the samples.Statistical analysis indicated that leachings from septic tanks were at least partially responsible for the contamination of shallow water supply sources with nitrate, phosphate, chloride and arsenic. Iron, lead and manganese appear to have come from corrosion of antiquated plumbing in older homes.     

Detection of enteroviruses in untreated and treated drinking water supplies in South Africa

Enteric viruses have been detected in many drinking water supplies all over the world. A meaningful number of these supplies were treated and disinfected according to internationally acceptable methods. In addition, counts of bacterial indicators (coliform bacteria and heterotrophic plate count organisms) in these water supplies were within limits generally recommended for treated drinking water and these findings have been supported by epidemiological data on infections associated with drinking water. The shortcomings of conventional treatment methods and indicator organisms to confirm the absence of enteric viruses from drinking water, was generally ascribed to the exceptional resistance of these viruses. In this study, the prevalence of enteroviruses detected from July 2000 to June 2002 in sewage, river-, borehole-, spring- and dam water as well as drinking water supplies treated and disinfected according to international specifications for the production of safe drinking water was analysed. A glass wool adsorption-elution technique was used to recover viruses from 10--20 l of sewage as well as environmental water samples, in the case of drinking water from more than 100 l. Recovered enteroviruses were inoculated onto two cell culture types (BGM and PLC/PRF/5 cells) for amplification of viral RNA with nested-PCR being used to detect the amplified viral RNA. Results from the study demonstrated the presence of enteroviruses in 42.5% of sewage and in 18.7% of treated drinking water samples. Furthermore, enteroviruses were detected in 28.5% of river water, in 26.7% of dam/spring water and in 25.3% of borehole water samples. The high prevalence of coxsackie B viruses found in this study suggested, that a potential health risk and a burden of disease constituted by these viruses might be meaningful. These findings indicated that strategies, other than end-point analysis of treated and disinfected drinking water supplies, may be required to ensure the production of drinking water that does not exceed acceptable health risks. More reliable approaches to ensure acceptable safety of drinking water supplies may be based on control by multiple-barrier principles from catchment to tap using hazard assessment and critical control point (HACCP) principles.