An extensive nationwide study by the U.S. Geologic Survey has found evidence of pharmaceuticals including antibiotics and hormonal drugs, such as birth control pills, in surface waters throughout the nation.
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Whether the presence of drugs in water translates into human health impacts is still being studied. But research has shown that drugs containing hormones such as estrogen are causing changes and deformities in fish and other aquatic creatures.

The World Health Organization indicates that human risk assessments have shown low concentrations of pharmaceuticals in drinking water have a negligible health risk. But WHO points out that long-term exposures have not been evaluated, especially in populations with other illnesses or with compromised immune systems. Also, according to the WHO, antibiotics in water supplies are a potential concern because the most frequently used antibiotics are becoming less effective as the infections they are designed to combat become resistant.