A system for detecting the presence of E. coli and total coliform in a water sample includes a sample holder that holds smaller, divided volumes of the sample and a testing reagent. A plurality of light sources are disposed above sample holder. The divided sample volumes are are illuminated with first and second light sources emitting light at different wavelengths. A bundle of optical fibers is provided with having an input end located adjacent to the divided sample volumes and is configured to receive light passing through the sample volumes. Light is output from the bundle of optical fibers and is captured with a camera. Image processing software is provided and is configured to calculate a light intensity in first and second wavelength channels at different times and outputs a positive/negative indication for E. coli and total coliform for the water sample.