A sensitive presence/absence test kit for detection of coliforms in drinking water

Coliforms are the most widely accepted bacterial indicator of fecal pollution in water. Several commercially available portable kits make it possible to carry out on-site water quality testing, but are usually costly and often require technical expertise to operate. In developing countries like India, presence/absence test kits like the H₂S test kits are commonly used for routine microbiological water quality examination. H₂S test kits require an incubation time of more than 24 hours and often gives false positive results. In this research work, we have developed a low-cost and sensitive test kit (ColiPAT) for the detection of coliforms including Escherichia coli in drinking water. The kit can detect very low contamination levels down to 2 coliforms/100 mL within 18 hours at 35 °C. The ColiPAT kit does not lose its sensitivity in the typical indoor temperature range of 27 °C to 35 °C. ColiPAT is also affordable and easy to perform so that local populace can conduct the test independently. This paper presents the results of sensitivity and specificity analysis of a ColiPAT kit and its comparison with the H₂S test kits as standardized using Colilert method.