Evaluation of the presence-absence (P-A) test: A simplified bacteriological test for detecting coliforms in rural drinking water of India

One thousand three-hundred and ninety-four drinking water sources comprising ground water, surface water and piped supplies were tested in order to compare the presence-absence (P-A) test with standard MPN method to detect coliforms as indicators of water quality. Out of 1394 samples, 1074 (77.04%) and 1030 (74.88%) were positive by the MPN and P-A test, respectively. The P-A test detected 96% of the positives detected by the MPN test. The P-A test may be effectively used as a rapid screening method to detect coliform contamination in less polluted sources such as ground water and piped supplies.