Presence-absence (P-A) broth, dehydrated 500 g

The Presence/Absence (P/A) test is a qualitative method used to detect coliforms and E. coli in treated waters. Unlike the Most Probable Number and Membrane Filtration tests, the P/A test provides a simple "yes" or "no" answer regarding the presence of these organisms, without indicating their quantity. (The maximum contaminant goal of zero total coliforms in drinking water eliminates the need to enumerate coliforms in samples). Additional screening of the sample for fecal coliforms, Pseudomonas, fecal streptococcus, and others can be done by selecting an appropriate confirmation method.