The study aimed to: (1) determine the sensitivity and specificity of PHC bottle as a screening test for determining the safety of drinking water; (2) determine the safety of drinking water; (3) correlate the lenght of time it takes the PHC bottle to turn black and the most probable number of colliform organisms present (MPN) and (4) determine the reliability of the results of the analysis as conducted/reported by the barangay health workers.
A simple field test for the detection of fecal contamination of water supplies was assessed in terms of its comparability with conventional water bacteriologic tests, its objectivity and validity. The results of this field test showed 82 agreement with those of combination-tests of Coliform Index, E. coli Test and colony count. Using the 3-combination-tests as reference, the PHC test had a sensitivity of 67.1 and a specificity of 100. Its positive result had a predictive value of 100 while a negative result had a predictive value of 88.9 . The percent agreement in the readings of the tests done by a health professional and members of water maintenance committees was 98.The test is fairly accurate, objective, precise and practical and together with the sanitary inspection of the water system, can be used as a tool for monitoring the bacteriological quality of drinking water.