Through Bacteriological Monitoring, Volunteer Monitors detect levels of E. coli and other coliform bacteria in water as indicators of fecal contamination. Monitors are trained in bacteriological sampling (site selection, plating and incubating samples, and counting bacteria colonies) and water quality standards.
E. coli
Escherichia coli (E. Coli) is a single species of fecal coliform that exists in about 700 forms, or strains. The vast majority are harmless, but a few are highly pathogenic. The presence of E. coli in food or water is a sure sign of fecal contamination.
Other coliforms
Alabama Water Watch uses a simple, inexpensive, and accurate method to quantitatively identify the presence of E. coli. The concentration of E. coli cells, or the number per unit volume of water is directly related to the probability that the water also carries other disease-causing pathogens. Therefore, if E. coli is present in a waterbody, it is possible that other pathogenic bacteria, viruses, protozoa, etc. are also present.
The bacteriological test used by AWW does not distinguish the source of E. coli, whether it be human, livestock, wild animals, etc. Citizens can get a general idea of the potential source of E. coli in their samples by surveying land use surrounding the sample site.
Water Quality Standards for E. coli in Water
AWW wants to be reasonable and conservative with our standards, so we use a stoplight method for interpreting bacteriological data where we consider water to meet water quality standards if the number of E. coli colony forming units (CFU) in 100 mL of water is between zero and 200. We warrant caution if the number of E. coli CFU in 100 mL of water falls between 200 and 600. If the number of E. coli falls above 600, there is high risk for human contact.
From May to September, anything above 300 E. coli CFU per 100 mL does not meet standards for Swimming and Other Whole Body Water Sports.
High E. coli levels indicate contamination from wildlife, runoff containing pet manure, agricultural runoff, wastewater treatment plants, and on-site septic systems. Human contact with such water can cause gastrointestinal illness, skin, ear, respiratory, eye, neurologic, and wound infections. Excess bacteria and other decomposers reduce dissolved oxygen.