The fecal coliforms comprise a portion of the total coliform group and are considered to be restricted by source to the intestines of warm blooded animals.
Bacteria included in the fecal coliform group are members of the genera klebsiella, escherichia, serratia, and erwinia. Of these, escherichia and klebsiella may be pathogenic to man under appropriate conditions. Escherichia may be responsible for infant diarrhea while certain species of klebsiella are responsible for a small percentage of the bacterial pneumonias in the United States.
By definition, the fecal coliforms are those Gram negative, non-spore forming bacteria which ferment lactose to acid and gas in 24 hours at 44.5° C.
Since the fecal coliforms are restricted to the intestinal tracts of warm-blooded animals, they are of more sanitary significance than the total coliforms when evaluating drinking water supplies or recreational waters.
Since the soil bacteria (entrobacteria) are not included in the fecal coliform group, fecal coliform counts should always be less than total coliform counts within the same sample.
The condition of bathing waters varies from day to day and season to season and it may be altered by permanent sources of pollution. The incidence of disease among local population, the bathing load, wind, weather, temperature and the composition of water must all be considered when doing bacterial studies for drinking or recreational uses of water.