Abstract: A bioluminescent assay for ATP in water borne bacteria is made by adding nitric acid to a water sample with concentrated bacteria to rupture the bacterial cells. The sample is diluted with sterile, deionized water, then mixed with a luciferase-luciferin mixture and the resulting light output of the bioluminescent reaction is measured and correlated with bacteria present. A standard and a blank also are processed so that the light output can be correlated to bacteria in the sample and system "noise" can be substracted from the readings.A chemiluminescent assay for iron porphyrins in water borne bacteria is made by adding luminol reagent to a water sample with concentrated bacteria and measuring the resulting light output of the chemiluminescent reaction. The light output is correlated with bacteria present. A standard and a blank are also processed so that the light output can be correlated to bacteria in the sample and system "noise" can be subtracted from the readings.