FREQUENCY OF E. COLI IN WATER SAMPLES FROM FILTRATION PLANTS OF LAHORE DISTRICT

Abstract

Background: Clean and safe drinking water is fundamental for public health and well-being. Globally, microbial contamination of water is a persistent issue, especially in urban areas with aging infrastructure and poor sanitation. Escherichia coli (E. coli), a fecal indicator organism, serves as a critical marker of contamination and potential pathogenic presence. In cities like Lahore, Pakistan, challenges such as unregulated urban expansion, outdated filtration systems, and limited maintenance have increased the vulnerability of water sources to fecal contamination.

Objective: To determine the frequency of E. coli contamination in water samples from public filtration plants in Lahore, assess associated environmental and operational factors, and evaluate the effectiveness of preventive measures.

Methods: A cross-sectional study was conducted over three months in Lahore, during which 178 water samples were collected from filtration plant outlets using simple random sampling. Each 100 mL sample was transported in sterile conditions to the Institute of Public Health, where E. coli detection was performed using the Multiple Tube Fermentation (MTF) method. Sanitary conditions around the plants were documented, and physical water characteristics (color, odor, pH, temperature) were recorded. Data were analyzed using SPSS version 20.0, with descriptive statistics and Chi-square tests applied. A p-value of ≤0.05 was considered statistically significant.

Results: Of the 178 samples, E. coli was detected in 54 (30.8%). Contamination was significantly higher in plants near sewerage lines (47.8%) compared to those without nearby sewerage infrastructure (6.3%) (p < 0.001). Plants with prior contamination history showed a 55.9% positivity rate. Preventive measures such as scheduled chlorination and sealing of open areas showed 0% contamination, while sediment filter-only systems had the highest contamination rate (54.1%). Community complaints were reported in 60.3% of locations, with 46.8% correlating with laboratory-confirmed contamination.

Conclusion: The study highlights substantial E. coli contamination in Lahore’s public filtration systems, with strong links to inadequate maintenance, environmental exposure, and lack of effective preventive strategies. Policy-level interventions, infrastructure upgrades, community education, and strict adherence to testing and disinfection protocols are crucial to ensuring safe drinking water.