I spent a summer working for the Texas Natural Resource Conservation Commission while in college. In addition to natural resources, it oversaw waste water treatment and solid waste disposal (land fills). The effluent from a water treatment facility (at least in Texas) is cleaner than the body of water into which it flows. At least one facility manager would prove the point by drinking a glass of said water, directly from the exit pipe, during regulator inspection tours. Anyone freaked out by this should think hard about the animals frolicking in their reservoirs...