Abstract:
Background: In Sri Lanka, public water sources are widely used for drinking and washing
purposes, yet concerns about their safety persist. This research highlights the importance of
identification of Escherichia coli (E. coli) contamination in public water sources that will aid in
the control of health risks. Regular monitoring of water sources for E. coli is crucial to ensure
drinking water safety, where E. coli is one of the main pathogens causing a spectrum of diseases.
This study focuses on assessing E coli contamination of public water sources at selected railway
stations in the Colombo district, Sri Lanka.
Objective: To determine the presence of E. coli in tap water available at railway stations in the
Colombo district, Sri Lanka
Methods: This cross-sectional study investigated the presence of E. coli in tap water from 30
railway stations. Water samples were collected in sterile amber-colour glass bottles and
transported in ice boxes following established protocols. The membrane filtration method was
performed under vacuum pressure utilizing a 100 mL sample volume. Then, membrane filters
were placed on Eosin Methylene Blue (EMB) agar and incubated at 35 °C for 24 hours. E. coli
was identified by their characteristic shiny, metallic, greenish-coloured colonies.
Results: The findings revealed that 36.66% of the samples contained bacteria. Among the bacteria
positive samples, one sample (3.33%) was found to be positive for E. coli, with a colony count of
7 CFU/100 mL. According to the Sri Lanka Standards Institute (SLSI) guideline for drinking
water, the acceptable limit for E. coli is 0 CFU/100 mL. The remaining 33.33% of the positive
samples contained other bacterial species. Positive bacterial samples included 3.33% Gram-
positive cocci, 10% Gram-negative cocci, and 23.33% Gram-negative bacilli.
Conclusions: The findings indicate bacterial presence in a considerable number of water samples.
E. coli contamination was found in one of the tap water samples taken from a railway station.The
presence of E. coli indicates faecal contamination. Although with one sample contamination, this
may indicate a potential health risk to the public. Improved monitoring mechanisms, regular
testing, public awareness and sanitation measures are essential to ensure safe drinking water and
prevent the spread of waterborne diseases through public water resources
