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.     

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.     

Study of the impact of land use and hydrogeological settings on the shallow groundwater quality in a peri-urban area of Kampala, Uganda

A study to assess the impacts of land use and hydrogeological characteristics on the shallow groundwater in one of Kampala's peri-urban areas (Bwaise III Parish) was undertaken for a period of 19 months. Water quality monitoring was carried out for 16 installed wells and one operational protected spring to ascertain the seasonal variation. The aspects of hydrogeological setting investigated in the study were the subsurface unconsolidated material characteristics (stratigraphy, lithology, hydraulic conductivity, porosity and chemical content), seasonal groundwater depths and spring discharge, topography and rainfall of the area. Both laboratory and field measurements were carried out to determine the soil and water characteristics. Field surveys were also undertaken to identify and locate the various land use activities that may potentially pollute. The results demonstrate that the water table in the area responds rapidly to short rains (48 h) due to the pervious (10(-5)-10(-3) ms(-1)) and shallow (<1 mbgl) vadose zone, which consists of foreign material (due to reclamation). This anthropogenically influenced vadose zone has a limited contaminant attenuation capacity resulting in water quality deterioration following the rains. There is widespread contamination of the groundwater with high organic (up to 370 mgTKN/l and 779 mgNO-3/l), thermotolerant coliforms (TTCs) and faecal streptococci (FS) (median values as high as 126E3 cfu/100 ml and 154E3 cfu/100 ml respectively) and total phosphorus (up to 13 mg/l) levels originating from multiple sources of contamination. These include animal rearing, solid waste dumping, pit latrine construction and greywater/stormwater disposal in unlined channels leading to increased localised microbial (faecal) and organic (TKN/NO-3) contamination during the rains. The spring discharge (range 1.22-1.48 m3/h) with high nitrate levels (median values of 117 and 129 mg/l in the wet and dry seasons) did not vary significantly with season (p=0.087) suggesting that this source is fed by regional base flow. However, the microbial quality deterioration observed in the spring discharge after a rain event (median values of 815TTCs cfu /100 ml and 433 FS cfu/100 ml) was attributed to the poor maintenance of the protection structure. Identification and selection of appropriate management solutions for the protection of shallow groundwater in informal settlements should not only be based on water quality problems and the causal physical characteristics as demonstrated by this study, but also institutional and socio-economic factors.     

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.     

Faecal coliforms and faecal streptococci in streams in the new guinea highlands

Procedures used to assess faecal water contamination were developed in temperate regions and their applicability to tropical waters has been questioned. This paper reports a detailed study of faecal coliform and faecal streptococci concentrations in the streams of the Saka Valley in the Highlands of New Guinea. The Saka Valley supports large populations of humans and domestic pigs, whose faeces are washed into the streams by surface runoff following rain. Faecal coliforms and faecal streptococci, enumerated by the membrane filtration technique, were found to be excellent indicators of faecal pollution in the New Guinea Highlands. A consideration of faecal coliform to faecal streptococci ratios and other factors, leads to the conclusion that most faecal contamination derives from pigs. All waters investigated, with the exception of spring waters, were grossly contaminated with faecal material and these polluted streams provide the total domestic water needs of the New Guineans. The fluctuations in pollution levels are described and their association with water temperature, rainfall and turbidity is analysed. The interpretation of the water contamination data is made speculative by the lack of information on the coliform and streptococcal flora of fresh pig and human faeces under New Guinea Highlands conditions.     

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.     

Health-based targets for greywater reuse in residential schools in Madhya Pradesh,India

In line with developments in the water reuse sector, this paper applied quantitative microbial risk assessment (QMRA) techniques to seven greywater reuse systems used for recycling shower water for toilet flushing. The objective of the study was to establish a scientific basis for health-based greywater targets for India. It involved qualitative risk assessments and quantitative microbiological analysis using Enterococci, thermotolerant coliforms (TTC) and coliphage indicator organisms. Four conclusions are drawn from this study. Firstly, the systems indicated a low risk and high quality, and secondly that low levels of risk were present in systems, resulting in the recommendation of guideline of 5000 cfu/100 mL rather than 10 000 cfu/100 mL for greywater utilised for direct toilet flushing. Thirdly, disability adjusted life years (DALYs) are a useful indicator of risk for evaluating the performance of a greywater reuse system in addition to chemical/microbiological indicators DALYs, and finally that TTC are a useful surrogate microbial indicator for analysis of greywater in developing countries with limited analytical facilities.     

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.     

Survival of infectious Poliovirus-1 in river water compared to the persistence of somatic coliphages, thermotolerant coliforms and Poliovirus-1 genome

The microbiological quality of water is currently assessed by search for fecal bacteria indicators. There is, however, a body of knowledge demonstrating that bacterial indicators are less resistant to environmental factors than human pathogenic viruses and therefore underestimate the viral risk. As river water is often used as a resource for drinking water production, it is particularly important to obtain a valid estimation of the health hazard, including specific viral risk. This work was conducted to compare the survival of infectious Poliovirus-1 used as a pathogenic virus model to the persistence of, on the one hand, thermotolerant coliforms commonly used as indicators and on the other hand, to somatic coliphages and Poliovirus-1 genome considered as potential indicators. We studied the behavior of infectious Poliovirus-1 and the three (potential) indicators of viral contamination in river water at three different temperatures (4 degrees C,18 degrees C and 25 degrees C). This experiment was performed twice with river water sampled at two different periods, once in winter and once in summer. Our results showed that the survival of thermotolerant coliforms can be 1.5-fold lower than infectious Poliovirus-1. In contrast, under all our experimental conditions, somatic coliphages and Poliovirus-1 genome persisted longer than infectious Poliovirus-1, surviving, respectively, 2-6-fold and about 2-fold longer than infectious Poliovirus-1. According to our results exclusively based on survival capacity, somatic coliphages and viral genome, unlike thermotolerant coliforms appear to be better indicators of viral contamination in river water. Moreover, the disappearance of viral genome is well-correlated to that one of infectious virus irrespective of the conditions tested.     

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.     

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.     

Fates of bacteriophages and bacterial indicators in the Moselle river (France)

It has been suggested that bacteriophages can provide useful information about the pathogenic microorganisms, particularly enteric viruses, present in water. This information is complementary to that obtained from bacterial indicators of faecal contamination, which would be of great value for evaluating the risks associated with the use of certain types of water. Before bacteriophages can be used as indicators of faecal contamination, we need to confirm that bacteriophages give a different response to that given by the well-known bacteria indicators and to determine what happens to bacteriophages in river water. Indeed, drinking water is often produced from river water, either by natural filtration through the soil or after undergoing various treatments. We collected 96 river water samples from six different sites between February and November 2000. The samples were analysed for three faecal indicator bacteria (thermotolerant coliforms, enterococci and spores of sulphite-reducing anaerobes) and three types of bacteriophages (somatic coliphages, F-specific phages and Bacteroides fragilis phages). The densities of thermotolerant coliforms and enterococci depended mainly on physical factors such as flow rate and water temperature. High temperature and low flow rate led to a decrease in the density of these microorganisms, especially in the absence of a major input of faecal pollution. Conversely, the densities of somatic coliphages, F-specific phages and spores of sulphite-reducing anaerobes remained constant regardless of the flow rate and temperature. The density of Bacteroides fragilis phages was too low for unambiguous determination of their fate in river water.     

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.     

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.     

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.     

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.     

Monitoring source water for microbial contamination: evaluation of water quality measures

Watershed management programs often rely on monitoring for a large number of water quality parameters to define contaminant issues. While coliforms have traditionally been used to identify microbial contamination, these indicators cannot discriminate among potential contaminant sources. Microbial source tracking (MST) can provide the missing link that implicates the sources of contamination. The objective of this study was to use a weight-of-evidence approach (land use analysis using GIS, sanitary surveys, traditional water quality monitoring, and MST targets) to identify sources of pollution within a watershed that contains a raw drinking water source. For the study watersheds, statistical analyses demonstrated that one measure each of particulate matter (turbidity, particle counts), organic matter (total organic carbon, dissolved organic carbon, UV(254) absorbance), and indicator organisms (fecal coliforms, enterococci) were adequate for characterizing water quality. While these traditional parameters were useful for assessing overall water quality, they were not intended to differentiate between microbial sources at different locations. In contrast, the MST targets utilized (Rhodococcus coprophilus, sorbitol-fermenting Bifidobacteria, and male-specific coliphages) pinpointed specific sources of microbial pollution. However, these targets could not be used for routine monitoring due to a high percentage of non-detects.     

An Assessment of the Impact of Inland Surface Water Input to the Bacteriological Quality of Coastal Waters

The introduction of ultraviolet disinfection in Jersey has achieved significant improvements in water quality. However, bathing waters in St Aubin's Bay and shellfish flesh have failed to comply with microbial standards. Streams and seepages from coastal structures were investigated as potential indicator organism sources (total and faecal coliforms, faecal streptococci). Seepages were an unimportant bacterial source as concentrations were low. Geometric mean concentrations in streams were up to four orders of magnitude higher than in final sewage-treatment works effluent, and concentrations increased significantly at high stream discharge. Rainfall-induced pulses of poor water quality occurred two to three times per week during the 1993 summer season. Natural discharges from island catchments thus contribute significantly to the bacterial load received at the coast, especially during high flow events. These observations have implications for other UK and European schemes using tertiary disinfection technology to attain water quality targets in coastal waters.     

Faecal indicator pollution from a dairy farm in Ayrshire, Scotland: source apportionment, risk assessment and potential of mitigation measures

The objectives of this study were (i) to apportion sources of faecal coliforms (FC) and faecal streptococci (FS) loads from a dairy farm to a stream in the Irvine catchment; (ii) to assess efficacy of pollution mitigation measures installed on this farm; (iii) to assess frequency with which observed FC loads contribute to high risk of failure of coastal bathing water to meet microbial standards. FC and FS loads in a primary stream running through the farm were estimated at up to four stations (above the farm, above the steading, below the farm and below a pre-existing 0.6 ha area of open water/wetland), in summer 2004 and 2005. During this period, steading and field mitigation measures were being installed. We estimated that farm FC loads likely to cause bathing water failure were 8.9 x 10(8) colony-forming units (cfu) ha(-1)d(-1) (guideline standards) and 1.7 x 10(10)cfu ha(-1)d(-1) (mandatory standards). In 2005, the guideline exceedance risk (42%) was associated about equally with field and steading sources, whereas the mandatory exceedance risk (11%) was mainly due to steading sources. The pond/wetland below the farm reduced these exceedance risks to 20% and <1%, respectively, but was a source of FS at high discharge. The exceedence curves below the farm were similar in 2004 and 2005, despite lower flows and installation of pollution mitigation measures. The results suggest that further mitigation efforts on this farm should be focused on improving management of the steading FC sources and that wetlands to receive steading runoff can be cost:effective mitigation tools for faecal indicator pollution.