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.     

The quality of drinking water from private water supplies in Aberdeenshire,UK

The quality of private water supplies within Aberdeenshire sampled between 1992 and 1998 was analysed with respect to the presence of total coliforms (TC), faecal coliforms (FC), and nitrate. Of the approximately 1750 samples analysed, which included multiple samples from larger supply categories, the individual failure rate was 41%, 30% and 15% for TC, FC and nitrate, respectively. A combined failure rate for these samples was 48%. Failure rates on microbiological grounds displayed a seasonal trend being greater during the latter half of the year. Although this observation is likely to be due to a combination of local and regional scale factors, part of the variability in failure rate was explained by a significant positive relationship with rainfall amount. Concentrations of nitrate tended to display an opposite trend with a greater number of failures occurring during the spring period and no relationship with rainfall was immediately apparent. A relatively small number of samples (< 50) failed simultaneously for both coliforms and nitrate suggesting that the mechanism responsible for the contamination differed. A similar failure rate for samples collected directly from the source (i.e. well) compared with those taken from the potable tap (usually kitchen cold water tap) suggests that it is the groundwater source itself that contributes much of the microbiological and nitrate contamination rather than a storage or supply line contamination mechanism. A more frequent and random sampling of category one F supplies suggested a greater overall failure rate, which has its own implications for deciding an appropriate sampling frequency.     

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.     

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.     

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.     

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.     

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.     

Microbiological analysis of selected coastal bathing waters in the U.K., Greece,Italy and Spain

The study was undertaken to assess the performance of a selected range of holiday destinations against the microbiological determinants of the European Union (EU) bathing water Directive [Council directive of 8 December 1975 concerning the quality of bathing waters. Official Journal L,31, 1–7. 76/160/EEC.]. The destinations were situated in three Mediterranean countries —Greece, Spain and Italy— and in the U.K. itself. The Mediterranean destinations were chosen on the basis of their popularity with British visitors, the U.K. beaches on a fairly random basis. All the beaches in all countries were EU designated bathing waters, several holding the prestigious European Blue Flag award. Summary findings indicate that the five beaches sampled in Spain were all of very good microbiological quality for the ten days of sampling. Four of the beaches examined in Crete were of similar good quality. The fifth, at Malia, was of much poorer quality. The five Italian beaches all failed at least one of the Mandatory standards for either total or thermotolerant (faecal) coliforms. All these failures occurred on the same two days, coincident with heavy rainfall. The six U.K. beaches surveyed all passed Mandatory standards for total coliforms but one beach did not comply with the Mandatory standard for thermotolerant coliforms. The fact that several of the Mediterranean and U.K. beaches examined in the study were European Blue Flag beaches and that, on occasion, their water quality failed to meet the criteria for that award, suggests that such award schemes should clearly indicate that the guarantee of bather safety is far from absolute.     

Prospects for New Techniques for Rapid Bacteriological Monitoring of Drinking Water

The microbiological safety of water supplies is at present assured by monitoring for the absence of the faecal indicator organisms, total coliform bacteria and Escherichia coli. This monitoring work represents the bulk of the workload of microbiology laboratories in the water industry. The accuracy of current methods is not questioned, but the times taken to obtain a presumptive result (18 h) and a confirmed result (up to 72 h) impose delays, particularly with regard to the recommissioning of distribution systems. There is therefore a continued demand for more rapid techniques, which has not been satisfied, despite the advances in analytical methods which have been adopted in other industries. Alternatives to the traditional culture-based methods are reviewed in this paper, and promising techniques for water applications are highlighted. Highly specific bacterial labelling methods and sensitive instrumentation for detection and enumeration already exist, so that rapid same-day detection of coliforms is technically feasible. Suitable separation methods for rapid analysis of water samples have not yet been developed, but antibody-mediated separations which are now employed in clinical and food microbiology may be applicable.     

Efficiency of removal of coliforms, faecal coliforms and coliphages in the tubli sewage treatment plant, bahrain

Total coliforms, faecal coliforms and coliphages in the raw sewage were detected in high numbers during the months averaging a maximum temperature of 20°C. The secondary and tertiary effluents show a 99–100% removal of the three indicators of faecal pollution. A direct correlation between the faecal coliforms and coliphages suggests that coliphages alone may be used as an indicator for the presence of pathogenic bacteria in contaminated waters.     

The effect of physicochemical, phytoplankton and seasonal factors on faecal indicator bacteria in northern brackish water

The relationships existing between the numbers of coliforms, faecal coliforms, faecal streptococci, C. perfringens, certain physicochemical parameters, phytoplankton, and seasonal factors in an eutrophic northern brackish water were investigated during a period of 1 year. Seasonal fluctuation of the faecal indicator bacteria was noted. A highly significant correlation was found between the non spore-forming faecal indicator bacteria examined. Of the physicochemical parameters examined the pH-value and temperature were found to have the most effect on the number of faecal indicator bacteria but nutrients, especially total nitrogen and nitrate nitrogen were also significant. The lack of correlation between C. perfringens and the other indicator bacteria was found to be related, in part, to the variation in pH. Thus C. perfringens can be considered as a useful indicator in ecosystems having stress factors. The results in this study show that many stress factors affect the number of faecal indicator bacteria. Therefore it is necessary to estimate the quality of water using a combination of several parameters.     

The Quality of Private Water Supplies in Calderdale - the Implications of the EC Directive on Drinking Water Quality

T he NUMBER AND nature of private water supplies in Calderdale Metropolitan Borough Council, West Yorkshire, were determined and each of these supplies sampled once or more to determine their compliance with the 1985'EC Directive on drinking water quality'. A total of 560 private water supplies were located serving 1970 properties. Of a total of 1160 samples tested, 83 per cent failed to meet the maximum admissible concentration for one or more of the parameters specified in the EC Directive. These parameters monitored included faecal coliforms, for which 48 per cent of the samples failed, and lead, for which 25 per cent failed. Possible reasons for these failures are discussed and the implications of these results on the implementation of the Directive are considered.     

The impact of sunlight on inactivation of indicator microorganisms both in river water and benthic biofilms

A detailed knowledge on decay or inactivation kinetics of faecal indicator microorganism in rivers is essential for control of bathing water quality. Both reliable inactivation rate coefficients for such kinetics and the knowledge on pathogen accumulation in benthic biofilms are needed for the assessment of river self purification capability and for being able to make decisions for an optimized water management. Therefore, the inactivation kinetics for main indicator microorganisms like faecal coliforms and intestinal Enterococci in water and on stones of the river Isar (Germany) were measured at artificial sunlight radiation. A flume was built, containing Isar water and sediment. By adding a pulse of pre-treated sewage water, the subsequently change of indicator bacteria levels in the bulk and biofilm phase is measured. Bacterial inactivation was mainly dependent on sunlight intensity. Mean inactivation rate coefficients in the experimental set up with river water obtained for a radiation intensity comparable to average midday sunlight in June in 50 degrees north latitude (I((290-390nm))=40.0W/m(2)) were found to be 21.4d(-1) for faecal coliforms and 20.0d(-1) for intestinal Enterococci. For a radiation intensity conform with the annual mean radiation in Germany (I((290-390nm))=8.0W/m(2)) inactivation rate coefficients were 12.7d(-1) for faecal coliforms and 9.3d(-1) for intestinal Enterococci. A measurement without direct artificial sunlight (I((290-390nm))=0.08W/m(2)) yields inactivation rate coefficients of 3.4d(-1) for faecal coliforms and 1.7d(-1) for intestinal Enterococci, which were similar to those found in wastewater treatment ponds. Due to re-growth and better environmental conditions the concentrations of faecal coliforms and intestinal Enterococci within the biofilm were 10(2) to 10(4) fold higher compared to the bulk water depending on the exposure time.     

Concentrations of coprostanol that correspond to existing bacterial indicator guideline limits

Coprostanol is a faecal sterol that has been proposed as an alternative measure of faecal pollution. While the technique has been used successfully to trace sewage-derived organic matter in a range of environments, it has not been embraced for use as a water quality indicator. This is mostly because of a lack of epidemiological evidence relating coprostanol abundance to any health risk. However, there is a valuable reason why the concentration of coprostanol should be related as quantitatively as possible to the abundance of bacterial indicators currently used to measure faecal pollution. The measurement of coprostanol (and concurrently other faecal sterols) offers many diagnostic and quantitative advantages over traditional techniques for detecting human sewage pollution versus faecal contamination from animal sources. Knowing the amount of coprostanol expected given a certain amount of human sewage pollution would provide a measure against which water managers could quantitatively assess faecal pollution as a whole and relate that assessment to variables with which they are more familiar. This study determines the relationships between coprostanol concentrations and indicator bacterial counts and synthesises the results from several environments to propose coprostanol concentrations broadly equivalent to existing bacterial standards. Our data suggest that 60 and 400 ng L⁻¹ of coprostanol correspond to currently defined primary and secondary contact limits for bacteria measured as thermotolerant coliforms (commonly referred to as faecal coliforms) or enterococci.     

Assessing the improvement of the Bilbao estuary water quality in response to pollution abatement measures

To evaluate the success of almost 20 years of pollution abatement in the Bilbao estuary watershed in northern Spain, we analyzed temporal trends in pollution discharges and water quality from 1993 to 2003. Over that period a great portion of the raw wastewater discharge was intercepted and treated, leading to a significant reduction in the pollution load to the estuary (51.8% in biochemical oxygen demand, 70.9% in ammonia nitrogen and 81.9% in faecal coliforms). Temporal trends of mean annual levels of water quality variables showed statistically significant increases in dissolved oxygen saturation (between 2.04 and 4.11%/year) and decreases in ammonia nitrogen (between -4.15 and -175.75 microM NH3/year) and faecal coliforms concentrations (from 2.55 x 10(5) to 2.13 x 10(4) CFU/100ml). The improvement of the Bilbao estuary water quality reported in this paper is primarily attributed to the pollution abatement measures accomplished by the local water authority. Finally, as a result of these pollution control efforts, European bathing water quality standards were met at local beaches.     

Faecal coliforms and faecal streptococci community in the underground water in an equatorial area in Cameroon (Central Africa): the importance of some environmental chemical factors

A bacteriological and chemical study was carried out within 1 year on spring and well water of Yaounde. It assessed the importance of some chemical factors on some faecal bacterial communities. The monthly average densities of faecal coliforms and faecal streptococci varied, respectively, from 1 to 72 x 10(2) CFU 100 ml(-1), and from 1 to 31 x 10(2) CFU 100 ml(-1) of water. These bacterial abundances undergo spatio-temporal fluctuations. These spring and well waters which are slightly bicarbonate, are acidic, soft, with low to average mineralisation. Most of the chemical characteristics of these waters are relatively stable with time, with respect to apparent spatial fluctuations. The degree of correlation between chemical parameters and the abundance dynamics of isolated bacteria is heterogeneous. In an artificially constituted spring biotope, the increase in pH, electrical conductivity, concentration of dissolved oxygen, chloride, sodium, potassium, calcium and magnesium favoured (P<0.01) the abundance of faecal coliforms and faecal streptococci. The high concentration of dissolved CO2 reduces (P<0.001) the abundances of these bacteria. They would nevertheless have developed such a mechanism allowing to minimise inhibitory effects of some environmental factors. In the well water, the ecology of faecal streptococci and faecal coliforms undergoes a relative instability, probably due to the variability of the resultant interaction network.     

SEASONAL VARIATION OF BACTERIOLOGICAL AND CHEMICAL QUALITY OF DRINKING WATER: A CASE STUDY IN A PALESTINIAN DISTRICT

Evaluation of drinking water quality for Jenln district in Palestine was carried out for the years 1997, 1998, and 1999, respectively. Only 53.1 %, 85.4% and 69.6% of the drinking water samples tested for free chlorine residual, total coliforms and faecal coliforms, respectively are within the limits of the Palestinian and International standards. The seasonal variation of bacteriological and chemical quality of drinking water was investigated. It was found out that the summer season has the best quality and the winter has the worst. There remains some ignorance in testing the drinking water in the villages and towns in Jenin district. Huge efforts are required to improve the drinking water quality in Jenin district, as well as other Palestinian districts, through public awareness, training of governmental Inspectors, in addition to a strict monitoring system for water quality.     

Relationships between indicators,pathogens and water quality in an estuarine system

This study examined water and sediment samples for a range of indicator and pathogenic microorganisms from six sites in an urban estuary, Sydney, Australia. Water quality was affected by rainfall and sewage overflows which were associated with significant increases in the concentration of faecal coliforms, faecal streptococci, Clostridium perfringens spores, F-RNA bacteriophage, Aeromonas spp., Giardia and Cryptosporidium spp. However, in sediments, only faecal coliform concentrations were significantly increased by rainfall, although sewage overflow again resulted in increased concentrations of faecal coliforms, faecal streptococci, C. perfringens spores and Aeromonas. Isolation of Salmonella appeared to coincide with wet weather events and occasionally identical serotypes were detected in sediments at several locations within the estuary. However, isolations of enteric virus were sporadic and did not appear to be exclusively related to wet weather events. C. perfringens was identified as the most useful indicator of faecal pollution and was the only indicator significantly correlated to the presence of pathogenic Giardia (r = 0.41, p < 0.05) and the opportunistic bacterial genus Aeromonas (r = 0.39, p < 0.05). F-RNA bacteriophage was not significantly correlated with any of the pathogens examined.     

Statistical study of the relationship between free chlorine levels and bacteriological checks on systems in the Paris area

The majority of French cities are supplied with treated surface water. The primary factor in determining the quality of this water concerns disinfection to ensure that the system is not contaminated with parasites, coliforms and streptococci; some of these organisms, especially coliforms, are capable of multiplying within the system. The presence of bacteria indicative of faecal contamination in water samples, which contains a significant amount of free chlorine, has revealed a possible link between the two. Based upon sampling points of the Parisian system (and in the suburbs for purposes of comparison), we show the existence of a linear relationship between the results of analyses for coliforms on a given day, D, and the content of free chlorine in the water on days D-2 and D-3. Subsequent ground tests confirm the explanations proposed regarding these phenomena.