Many states have since adopted this recommendation, however, some still use total fecal coliform
bacteria when determining concentrations. The acceptable risk level for total body contact recreation,
which involves activities such as swimming or water skiing, is 126 colonies of organisms (referred to as
colony forming units or cfu) per 100 milliliters (ml) of water or less based on a geometric mean
(calculated over 30 days with at least 5 samples) or a one-time concentration of 235 cfu/100 ml. The risk
of getting sick increases as total numbers of colonies are exceeded.