Comparison of the bacteriological quality of tap water and bottled mineral water

The bacteriological quality of tap water from municipal water supplies, 20-L bottles of mineral water from water dispensers and samples collected from new 20-L bottles of mineral water were comparatively studied. Total coliforms, termotolerant coliforms, Escherichia coli, fecal streptococci, Pseudomonas aeruginosa, Staphylococcus spp. and heterotrophic plate count were enumerated. The results showed that 36.4% of the tap water samples from municipal water systems and 76.6% of the 20-L bottles of mineral water from water dispensers were contaminated by at least one coliform or indicator bacterium and/or at least one pathogenic bacterium. The bacteriological quality of municipal tap water is superior when compared with the 20-L bottles of mineral water collected from water dispensers and samples collected from new 20-L bottles of mineral water before installation in the dispensers. This highlights the need for an improved surveillance system for the bottled water industry. For the municipal water systems, it is recommended to perform the Pseudomonas enumeration periodically, in addition to the routine data collected by most systems.     

Environmental impact on the bacteriological quality of domestic water supplies in Lagos,Nigeria

OBJECTIVE: To assess the impact of town planning, infrastructure, sanitation and rainfall on the bacteriological quality of domestic water supplies. METHODS: Water samples obtained from deep and shallow wells, boreholes and public taps were cultured to determine the most probable number of Escherichia coli and total coliform using the multiple tube technique. Presence of enteric pathogens was detected using selective and differential media. Samples were collected during both periods of heavy and low rainfall and from municipalities that are unique with respect to infrastructure planning, town planning and sanitation. RESULTS: Contamination of treated and pipe distributed water was related with distance of the collection point from a utility station. Faults in pipelines increased the rate of contamination (p<0.5) and this occurred mostly in densely populated areas with dilapidated infrastructure. Wastewater from drains was the main source of contamination of pipe-borne water. Shallow wells were more contaminated than deep wells and boreholes and contamination was higher during period of heavy rainfall (p<0.05). E. coli and enteric pathogens were isolated from contaminated supplies. CONCLUSIONS: Poor town planning, dilapidated infrastructure and indiscriminate siting of wells and boreholes contributed to the low bacteriological quality of domestic water supplies. Rainfall accentuated the impact.     

Improving the standard and methodological basis for bacteriological monitoring the quality of drinking water

The paper presents materials to provide a scientific rationale for the microbiological parameters enhancing the efficiency of drinking water quality control from the point of view of reliability in the provision of epidemic water consumption safety (coliform bacteria being identified by the glucose index; E. coli). Based on the criterion assessment of the significance of microbial water contamination in relation to morbidity rates, the authors have been developed bacteriological standards--the absence of microorganisms in a 300-ml water sample. Evidence is provided for the epidemically significant level--more than 2 CFU of coliform bacteria in 100 ml. A rapid determination procedure has been substantiated in the experimental studies of the effects of oxidase reagents on the viability and biochemical properties of E. coli bacteria. In search for current technologies for membrane filtration, experimental rationale has been made for the possibility of using track membranes for sanitary and bacteriological water analyses.     

The preparation of simulated water samples for the purpose of bacteriological quality control.

As part of the bacteriological quality control programme of the Public Health Laboratory Service, we were asked to investigate the possibility of providing simulated water samples for distribution to the laboratories. For this purpose it was necessary to find some means whereby suspensions of coliform organisms and Escherichia coli could be kept relatively stable in number at room temperature for a period of 7-10 days. This, it was finally found, was best achieved by adding selected strains of the organisms to improved formate lactose glutamate medium (Gray, 1964) without the lactose but with added boric acid to a final concentration of 1-8%. The procedures adopted in the successful quality control programme are described.     

The bacteriological quality of traditional water sources in north-eastern Imo State, Nigeria.

Monthly bacteriological water testing of traditional water sources (ponds, rivers, unprotected springs and traditional wells) used by five villages in northeastern Imo State, Nigeria, was conducted during the period January 1983 to August 1985. The membrane-filtration technique was used to detect faecal coliforms (FC) and faecal streptococci (FS). Evidence of faecal pollution was seen throughout the year for all water sources. During the study period, the monthly geometric mean counts per 100 ml of water (all sources combined) ranged from 760 to 17877 for FC and from 678 to 17394 for FS. The peak period of faecal pollution occurred during the transition between the dry and wet seasons and in the early wet season. During this peak pollution season (February-May), the geometric mean counts were 2.5-7.2 times higher than in the remaining part of the year for all source types except rivers, with ponds being the most heavily polluted. Preliminary findings on the sensitivity and specificity, in this tropical environment, of the standard membrane-filtration technique for enumerating FC are presented. The implications of the findings of this study for the environmental control of waterborne and hygiene-related diseases are discussed.     

Physicochemical and bacteriological assessment of water quality at the Ross Barnett reservoir in central Mississippi.

The Ross Barnett Reservoir serves as a source of water supply for the city of Jackson, Mississippi, U.S.A. and is an important site for recreational activities for many residents of Mississippi counties. A broad spectrum of illness is associated with water-contact activities like bathing and swimming in recreational waters. In the present research, we assessed the bacteriological quality of water in the Ross Barnett Reservoir and compared the levels of bacteria with the recommended criteria for public health protection. From June 12, 1999 to October 2, 1999, we collected water samples weekly from two different sites in the reservoir and tested them for the following bacteriological parameters: heterotrophic plate counts, total coliforms, fecal coliforms, and fecal streptococci. The samples were also tested for basic physical and chemical characteristics of water. The results of the study indicate that the respective mean concentrations of bacteria (colony forming units per 100 mL of water) in water samples collected from the reservoir were 5.6 x 10(6)+/-1.5 x 10(6) (heterotrophic plate counts), 4.5 x 10(4) +/- 5.3 x 10(4) (total coliforms), 5.0 x 10(2) +/- 1.6 x 10(2) (fecal coliforms), and 9.1x10(1)+/-7.3x10(1) (fecal streptococci). The values of all physical and chemical parameters were at acceptable levels. The bacterial densities, however, often exceeded federal/state guidelines by several orders of magnitude, raising considerable public health concerns. Steps should therefore be taken to develop and implement strategies to improve the water quality and to reduce or eliminate the potential health risks associated with water-contact activities in the Ross Barnett Reservoir.     

Monitoring the bacteriological quality of potable waters in hospital

We report a survey of the bacteriological quality of potable waters from hospitals. In the 12-month period February 1986 to January 1987, 646 samples were examined from 25 hospitals. Coliforms were isolated from eight (1.2%) samples, received from three hospitals. These hospitals did not, therefore, satisfy the European Community (EC) directive on potable water quality. Three hundred and four (47%) samples had total viable counts higher than the guidelines given in the EC directive on potable waters. Thirteen (52%) of hospitals surveyed submitted at least one unsatisfactory sample and six (24%) submitted more than 50% unsatisfactory samples. Water quality was generally poorer in the summer and autumn. Estimation of the total viable count is an inexpensive and simple method for monitoring the microbial quality of hospital waters.     

An investigation of bacteriological and chemical water quality and the barriers to private well water sampling in a Southwestern Ontario Community

Private well owners in Canada are responsible for maintenance, including routine sampling, of their private drinking water supply. Sampling rates in a Southern Ontario community are well below the public health recommendation. A study with private well owners was conducted to improve private well water sampling rates through the removal of two significant barriers to private well water testing.During the pilot and extended study phases, 549 nitrate and 425 bacteriological water sampling bottles were delivered to private well owners and water samples were collected the following day. A follow-up telephone survey was conducted with both study participants and non-participants to identify barriers to private water sampling that were encountered by the study sample population.Participation rates in the pilot and extended study phases were less than 50% prompting the follow-up telephone survey. Inconvenience and lack of time [statistically significant, P < 0.01] were found to be the main barriers for participation in the study.The findings from this study illustrate the influence that certain barriers have on the frequency of private well water testing in a Southern Ontario community. The findings provide guidance for other health authorities to improve sampling rates.     

An investigation of bacteriological and chemical water quality and the barriers to private well water sampling in a Southwestern Ontario Community

Private well owners in Canada are responsible for maintenance, including routine sampling, of their private drinking water supply. Sampling rates in a Southern Ontario community are well below the public health recommendation. A study with private well owners was conducted to improve private well water sampling rates through the removal of two significant barriers to private well water testing.     

Waterfowl and the bacteriological quality of amenity ponds

This study investigated the impact of waterfowl on the bacteriological quality of village ponds in East Yorkshire, north-east England. Water and sediment samples were collected from ponds with and without resident ducks and geese; faecal indicator and potentially pathogenic bacteria were assayed by membrane filtration and by selective enrichment. Escherichia coli, faecal streptococci and, to a degree, Clostridium perfringens were more abundant in ponds with waterfowl; Salmonella was isolated in June-August from the sediment of a pond with waterfowl. The results suggested that the bacteriological quality of village ponds might be adversely affected by waterfowl. All water samples from ponds with waterfowl had faecal indicators at higher concentrations than EU requirements for bathing waters. Although these ponds are not bathing waters we suggest skin contact and accidental ingestion of water should be avoided.     

The water agar test: a new test to measure the bacteriological quality of cream.

A new test, the water agar test, is described that gives a qualitative index of the presence of bacteria that indicate contamination of the cream, poor storage conditions or both of these factors. The method is simple and requires little equipment. The bacteria grow in a film of diluted cream adsorbed on the surface of a non-nutrient base. After incubation at 30 +/- 0-5 degrees C. for 18-20 hr., a proteolytic and mucoid colony count is obtained which has the same percentage coefficient of variance as a standard plate count. An examination of the effect of storage at different temperatures on the types of bacteria present in cream showed that of all the tests done initially, only the water agar test could predict subsequent bacterial growth with any consistency. The multiplication of presumptive coliform organisms occurred even at 3-5 degrees C. Irrespective of the colony count, the methylene blue reduction time was not shorter than 7 1/2 hr. unless the bacteria were in the logarithmic phase of growth when sampled. A survey was made of the bacterial flora of 188 retail samples of double cream of 15 different brands. The age of the samples varied from freshly separated cream to cream that had been kept in the shop for a day longer than that recommended for sale. The water agar test was compared with the colony count, the presumptive coliform test, a confirmatory coliform count in violet red-bile agar, a lipolytic colony count, a staphylococcal count and the methylene blue reduction test.     

The bacteriological quality of drinking water in Haldwani block of Nainital district, Uttarakhand, India

A cross-sectional study was conducted to assess the bacteriological quality of water in Haldwani block, Nainital District, India. Stratified random sampling was used to categorize water sources and consumer points. In total, 108 samples were collected: 15 from the Gola river, 51 from water taps, 24 from water treatment plants and 18 from tube wells. Samples were tested for coliforms by the most probable number technique. Identification of species was done by standard procedures. Of 108 water samples, 58.8% were found to be polluted. All samples of water (n = 15) from different sites of the Gola river were found to be highly contaminated. Out of 24 water treatment plant samples, four samples were found unsatisfactory, while more than half (51.6%) of its supplies to water taps were polluted. From tube wells and their water taps, 88.8 and 60% samples were found safe for drinking respectively. Bacterial contamination of water treatment plants and their supplies indicates significant disparities in the efficiency of water treatment processes. Contamination of water taps of tube wells suggests leakage of pipes. There is an urgent need to improve these services to ensure the supply of safe water for consumers.