Bacteriological analysis of drinking water in relation to diarrheic illness in and around Khammam


Background: Drinking water is a major source of microbial pathogens in developing regions although, poor sanitation and food sources are integral to enteric pathogen exposure. Poor water quality, sanitation and hygiene are responsible for the majority of deaths a year world-wide and mainly through infectious diarrhea. Objectives: The objectives of this study were to evaluate the bacteriological quality of drinking water at the source and point of use, to analyze the relationship between the presence of bacteria in water and diarrheic illness. Materials and Methods: A cross-sectional study was conducted on 100 water samples collected from various sources-bore wells, municipal tap waters, wells, and mineral water plants and also from storage containers in the house. Simultaneously, stool samples were also collected from households and processed. Results: Out of 100 water samples majority of them were consuming municipal water 16 (32%), followed by mineral water 14 (28%). For storage majority of them were using the candle filter 17 (34%), followed by steel containers 13 (26%). Escherichia coli was isolated in candle filters in the majority of cases 10 (29.4%), Enterobacter isolated in steel containers 6 (23%). Only in 50% diarrheal cases similar bacteria were observed both in water and stool samples. Conclusion: Water has become non-potable after storage due to various hygienic practices. Water may get contaminated at various levels, which is responsible for diarrheic illness. Safe water is essential for health. An efficient and well-maintained distribution system coupled with good hygienic practices would ensure that water is safe at the point of collection and before consumption.

Keywords: Diarrheic illness, Escherichia coli, potability, water analysis

How to cite this article:
Anuradha B, Praveena D. Bacteriological analysis of drinking water in relation to diarrheic illness in and around Khammam. Ann Trop Med Public Health 2013;6:618-21
How to cite this URL:
Anuradha B, Praveena D. Bacteriological analysis of drinking water in relation to diarrheic illness in and around Khammam. Ann Trop Med Public Health [serial online] 2013 [cited 2021 Mar 4];6:618-21. Available from:

Water has a great potential of transmitting a variety of enteric diseases. Contaminated water has been associated with an occurrence of disease outbreak particularly in communities living in areas with poor hygiene sanitation. It is estimated that about 10 million people in developing countries die annually from waterborne infections, half of them are children under the age of 5 years. [1] The World Health Organization (WHO) estimated that up to 80% of all sicknesses and diseases in the world are caused by inadequate sanitation, polluted water or unavailability of water. [2] Current WHO bacteriological guidelines for drinking water recommend zero fecal coliforms for 100 ml of water. Several parts of India are facing an immense challenge to meet the basic needs of safe water. Provision of safe household water includes the conditions and practices of water collection, storage, handling and choice of storage containers and vessels. [3] Water may become contaminated at any point between collection, storage, serving or handling in houses. [4] Microbial contamination of collected and stored house hold water is caused not only by collection and use, but unsanitary and inadequately protected (open, uncovered or poorly covered) water collection and storage containers. Unsanitary methods to dispense water from household storage vessels, including contaminated hands and dippers and inadequate cleaning of vessels, which lead to accumulation of sediments and pathogens. [5] The personal and domestic hygiene practices indirectly depend on the education of family members, water hygienic education, socio-cultural status, number of children in the house etc. [6],[7],[8]

The present study was conducted to evaluate the bacteriological quality of drinking water, risk factors influencing water quality and also examining the relationship between the presence of these bacteria in drinking water and prevalence of diarrheal disease in a population that consumed this water.

Materials and Methods

A cross sectional study was conducted in and around Khammam, AP. Ethics Committee clearance was obtained. Informed consent was taken. A total number of 100 drinking water samples along with stool samples of patients suffering with diarrheic illness were collected. Water samples from houses without diarrheic illness were excluded from the study. Drinking water samples were collected from different sources such as bore wells, municipal tap water, wells and mineral water plants. Samples were also collected from storage vessels using the pots, steel containers, water cans, candle filters and aqua guards.

They were labeled and transported to the laboratory for bacteriological analysis within 2 h of collection.

Along with water samples, stool samples were also collected from the same household with diarrheic illness into sterile containers avoiding urine contamination. The samples were processed to isolate pathogenic bacteria.

Water samples were tested by total coliform count and most probable number (MPN) was estimated to know the potability of water and specific pathogens in stored drinking water were tested by rapid Hi selective H 2 S medium Kit (powder form) K022 (Himedia laboratories, India). Hi selective H 2 S medium was a modification of the medium developed for the simultaneous detection of SalmonellaVibrioCitrobacter species and Escherichia coli from water samples. The organisms were identified as per the manufacturer’s instructions.

The stool samples were inoculated into Selenite F broth, alkaline peptone water and nutrient broth and incubated at 37°C for 24 h. After incubation observed for turbidity and sub cultured onto MacConkey agar, Leifson’s Deoxycholate citrate agar, Thiosulphate Citrate Bile Sucrose agar and Wilson and Blair brilliant green bismuth sulphite agar. The organisms were identified by standard procedures.


100 drinking water samples were collected from various sources and also from storage containers. Stool samples were also collected from diarrhea patients of the same house. Based on the source of water, samples collected were from municipal tap water 32 (32%), bore wells 24 (24%), well water 16 (16%), mineral water 28 (28%) [Table 1].

Table 1: Drinking water samples based on source

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Based on storage of drinking water, 34 samples (34%) were stored in candle filters, 20 samples (20%) were stored in pot containers and 26 samples (26%) in steel containers, 8 samples (8%) used aqua guards and 12 samples (12%) in water canes [Table 2].

Table 2: Drinking water samples based on storage containers

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Out of 100 samples only 84 (84%) samples showed bacterial growth. Rests of the 16 (16%) samples were sterile. Bacteria isolated from drinking water based on storage are shown in [Table 3]. Predominant bacteria isolated in candle filters were E. coli 10 (29.4%). In pot containers, Pseudomonas was predominant 8 (40%). In steel containers, Enterobacter 6 (23%), in aqua guards Pseudomonas 4 (50%) and in water cans storage containers E. coli 4 (33.3%) were predominant.

Table 3: Bacteria isolated from drinking water samples based on storage

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Among the 100 diarrheal cases Ecoli was isolated in 32 cases (32%), Shigella flexneri in 6 cases (6%), Shigella dysentriae in 4 cases (4%), Salmonella typhi in 6 cases (6%), Pseudomonas in 18 cases (18%), Proteus in 14 cases (14%) and Klebsiella 20 cases (20%). S. typhi was isolated in 4 cases (8%) of water as well as in diarrheic stool sample of patient. S. flexneri was isolated in 4 cases (8%), S. dysentriae in 2 cases (4%), E. coli in 20 cases (40%), Pseudomonas in 12 cases (24%) and Klebsiella 8 cases (16%) of both water and stool sample of the same house [Table 4].

Table 4: Bacteria isolated from the stool and water samples of the same house and its correlation with diarrheic illness

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Most probable number was estimated by total coli form (presumptive coli form) count and water was graded as potable and non-potable depending on the MPN counts before and after use [Table 5].

Table 5: Potability of water before use and after use

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The consumption of drinking water with pathogenic microbes of fecal origin was a significant risk to human health in the developing world. [9] Microbiological contamination of water between source and point of use was wide spread and was often significant. Increased fecal and total coliform count in household stored water containers were generally high even when the source of water was good quality, suggesting that contamination was wide spread during collection, transport, storage and drawing of water. [10] Water must be stored and drawn in a safe manner otherwise water may be re contaminated by communal drinking cup or dipper on the top of the covered storage vessels, touching the water with soil hands. E.g., anal cleaning. In this way, bacteriological quality of drinking water significantly decline after collection and water quality deterioration occur between the point of supply and consumption. [11]

The present study was conducted on patients suffering from diarrheic illness in relation to water contamination. Our study indicates that there were several transmission routes of diarrheal disease and various levels of water contamination. Here, majority of samples were potable at the source, but after storage and use they became non-potable due to poor personnel hygiene and storage practices and other cultural and socio-economic factors.

Among the 100 cases of diarrheic illness in 50 cases same organisms were isolated from both stool sample and water sample, which indicates that consuming such contaminated water, was responsible for diarrhea. Among the remaining 50 cases of diarrheic illness, 34 cases were consuming non-potable water, but pathogens like Salmonella and Shigella rarely survive in water for few days and testing for these pathogens may miss the diagnosis. Another reason was that release of pathogens from patients was usually in small numbers and when compared with volume of large water bodies the number would be relatively low thus increasing the chance of the pathogen to escape the laboratory detection, but the coliform count of these water samples was high.

The remaining 16 cases of diarrheic illness were using potable water, but the reasons for diarrhea may be eating and drinking outside the house and may not be by consuming household drinking water. Several investigators have reported difficulty in using total and fecal coliforms to measure the sanitary quality of tropical waters including the ability of bacteria to multiply, survive for long periods, and to occur in high numbers in the absence of any identifiable source of fecal pollution. [12]

Briscoe has proposed that removal of waterborne transmission route might not result in a substantial reduction in the rate of diarrheal disease because of effects of other routes and that improvement in water quality without concurrent improvements in sanitation and excreta disposal practices are not sufficient to significantly reduce the incidence of diarrhea. [13]

In one study from Philippines and Malawi on water supply, sanitation in diarrhea suggests that improved water supply was not enough to reduce the diarrheal disease, but the combined effect of improved water and sanitation was associated with reduction in diarrheal morbidity. [14]

In one study by Wibowo and Tisdell showed that safe water and sanitation were efficacious in improving the health status and reduces the morbidity from both water borne diseases as a whole, and for diarrhea in particular. [15]

In one study by Esrey et al. suggested that provision of sanitation may be more effective than safe water in reducing morbidity from waterborne diseases. [16]

Our study suggests that there was increased bacterial contamination of water from the source and points of use. The pathogens are transmitted by feco-oral route by contaminated food, hands and utensils. Use of scoops or bowls to draw water from the storage containers would be a risk factor to the bacteriological quality of stored water. That was the reason in our study same bacteria was isolated from water and diarrheal stool in some cases.

Summary and Conclusion

Seriously polluted water supplies were used by at least 1500 million people world-wide. The WHO guidelines for bacteriological quality of drinking water require that all waters intended for drinking water must contain no E. coli or thermo tolerant coliforms in any 100 ml samples. In addition to feco-oral route, other vehicles of transmission namely contaminated food, hand or utensils can also play a role.

The study indicates that water quality deteriorates as a result of multiple factors linked to hygiene practices and circumstances.

Safe water is essential for good health. All efforts must be taken to safeguard its quality at all stages of distribution. An efficient and well maintained distribution system coupled with good hygiene practices would ensure that water will be safe at the point of collection and before consumption.

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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1755-6783.1402222


[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]

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