Biological Contaminants Breakdown

Potential Contaminant	Contamination Source	Health Standard	Human and Environmental Effects
Blue-Green Algae	Naturally occurring but generally compete well in low light conditions; warm temperatures; and high nutrient concentrations. Presence of gas vacuoles and nitrogen fixing ability enhance competitive nature.	N/A	Diarrhea, vomiting, and nausea, if consumed. Potentially poisonous blooms affecting humans have been attributed to Anabaena, a blue-green heterocystic filamentous algae; can cause odor in clarified drinking water. Surface blooms; increased organic matter upon decomposition; release of toxic chemicals; noxious odors in some species; not readily cycled through grazer food chain thus decreased food sources for primary consumers.
Cryptosporidium	Cryptosporidium is a microscopic waterborne parasite. It can be spread by person to person contact; handling of fecal material; drinking water or eating food contaminated with the oocysts.		Watery diarrhea, abdominal cramps, nausea, weight loss, low grade fever.
Fecal Coliform Bacteria (E. coli) and Total Coliform	Human sewage; animal wastes; septic systems. Total Coliform is an indicator organism	Membrane filter - less than 1/100ml. Fermentation tube - no coliform presence allowed.	For coliform bacteria: may include diarrhea, cramps, nausea, and other gastrointestinal problmes.
Giardia	Giardia lamblia, which is found in untreated water and carried by human or animal fecal matter. Round hardened cyst is ingested by other humans, animals.	no MCL	Diarrhea, intestinal gas, nausea, and abdominal cramps; generally not fatal.
Legionella	Inhalation of contaminated air.	no MCL	Pneumonia-type symptoms
Other Bacteria	Human sewage; animal wastes; septic systems.		In households, cause staining, unpleasant odors and taste. Pathogenic bacteria may cause gastrointestinal illness and influenza-like illnesses when ingested. Heterotrophic and Autotrophic bacetria can create severe problems with taste, odor, and appearance
Viruses	Septic tanks; human sewage; animal waste. Possibly disposal of municipal water, sludge application to land, landfill oxidation ponds, or deep well injection of sewerage.	No MCL; EPA imposed treatment requirements that public utilities must use to remove or inactivate pathogens.	Hepatitis A one of most frequently reported viruses in water causing fever, nausea, diarrhea, and hepatitis. Other viruses imposing health threat include poliovirus, Norwalk, adenovirus, and retrovirus. Over 110 types of human enteric viruses identified.