Fecal coliforms are capable of growth in the presence of bile salts or similar surface agents, are oxidase negative, and produce acid and gas from lactose within 48 hours at 44 ± 0.5°C.
[2] Coliform bacteria include genera that originate in feces (e.g. Escherichia, Enterobacter, Klebsiella, Citrobacter).
[1] In general, increased levels of fecal coliforms provide a warning of failure in water treatment, a break in the integrity of the distribution system, possible contamination with pathogens.
Fecal coliform bacteria can enter rivers through direct discharge of waste from mammals and birds, from agricultural and storm runoff, and from human sewage.
Some older industrial cities, particularly in the Northeast and Midwest of the United States, use a combined sewer system to handle waste.
During high rainfall periods, a combined sewer can become overloaded and overflow to a nearby stream or river, bypassing treatment.
Runoff from roads, parking lots, and yards can carry animal wastes to streams through storm sewers.
Swans, geese, seagulls, and other waterfowl can all elevate bacterial counts, especially in wetlands, lakes, ponds, and rivers.
Agricultural practices such as allowing livestock to graze near water bodies, spreading manure as fertilizer on fields during wet periods, using sewage sludge biosolids and allowing livestock watering in streams can all contribute to fecal coliform contamination.
Aerobic decomposition of this material can reduce dissolved oxygen levels if discharged into rivers or waterways.
Fecal coliform, like other bacteria, can usually be inhibited in growth by boiling water, treating with chlorine, or UV disinfection.
Assays typically include a second sugar linked to a different dye, which produces a fluorescent product when acted on by the enzyme beta-glucuronidase.
[5] In 1989, the U.S. Environmental Protection Agency (EPA) published its Total Coliform Rule (TCR), which imposed major monitoring changes for public water systems nationwide.