Assessment of Reliability of H₂S Strip Test for the Screening of Drinking Water Samples for Faecal Contamination

The addition of human and animal excreta in drinking water causes biological contamination leading to serious health issues for consumers, especially in developing countries. The hydrogen sulphide (H₂S) paper-strip test is an inexpensive method for the detection of faecal contamination in water. This test is simple and easy to use and is widely used in developing countries like India for routine testing. This study was intended at evaluating the performance of the H₂S test method for the reliable detection of faecal coliforms in drinking water. The performance was assessed by matching its output against established tests used for the quantitative evaluation of faecal coliforms in drinking water. The Colilert-18 test and traditional spread plate method were used to compare the findings of 102 water samples that were examined using the H₂S test kit. The coliform detection limit of the H₂S kit was observed as 30.0 MPN/100 ml when incubated at 35 °C and requires up to 36 h of incubation time. The H₂S kit’s sensitivity and specificity were found to be 61.76% and 70.59%, respectively, indicating that it is an unsuitable test for detecting microbial contamination. The study suggests that there is an urgent need for the development of better alternatives.