Drinking Water Contamination from Peri-Urban Bengaluru, India

The presence of diarrhoeagenic bacteria such as Escherichia coli in drinking water indicates faecal and sewage contamination. Testing the microbial quality of drinking water at source (n = 29) and households (n = 43) of 29 peri-urban villages of Bengaluru city, indicated that 80% and 93% of samples respectively were unfit for human consumption as per WHO standards, i.e. nil E. coli in 100 ml sample. This also indicated that water gets contaminated further at the point-of-use when compared to the source. Forty-one per cent of the source drinking water samples had high E. coli counts which in turn means that the residing population face moderate to high risk of diarrhoea. A longitudinal study of the microbial quality of drinking water at source of supply (n = 45) was undertaken five times over an eight-month period in a subset of eight villages. Only around 18% of the total samples were microbially safe with nil E. coli/100 ml. Microbial contamination was found to be lower in January and March (<30 CFU/100 ml E. coli) when compared to December, May and September (>150 CFU/100 ml). Samples from Chikkakuntanahalli and Kodiyalakeranahalli had ≥1000 CFU/100 ml E. coli. Total dissolved solids, calcium, magnesium, alkalinity and hardness in source drinking water of eight selected villages were beyond acceptable levels. The nitrate levels were consistently high and beyond WHO permissible levels. Alarming levels of microbial and chemical contamination of drinking water from the sites press for appropriate remedial measures to reduce health threats, particularly among vulnerable population.