How many actually drink the water any more?
The 11 most frequently detected compounds - all found at extremely low concentrations - were:
• Atenolol, a beta-blocker used to treat cardiovascular disease
• Atrazine, an organic herbicide banned in the European Union, but still used in the US, which has been implicated in the decline of fish stocks and in changes in animal behaviour
• Carbamazepine, a mood-stabilising drug used to treat bipolar disorder, amongst other things
• Estrone, an oestrogen hormone secreted by the ovaries and blamed for causing gender-bending changes in fish
• Gemfibrozil, an anti-cholesterol drug
• Meprobamate, a tranquiliser widely used in psychiatric treatment
• Naproxen, a painkiller and anti-inflammatory linked to increases in asthma incidence
• Phenytoin, an anticonvulsant that has been used to treat epilepsy
• Sulfamethoxazole, an antibiotic used against the Streptococcus bacteria, which is responsible for tonsillitis and other diseases
• TCEP, a reducing agent used in molecular biology
• Trimethoprim, another antibiotic
Christian Daughton of the EPA's National Exposure Research Laboratory says that neither this nor other recent water assessments give cause for health concern. "But several point to the potential for risk - especially for the fetus and those with severely compromised health."
Snyder says water utilities could make drinking water purer. But the costs of "extreme purification" - far beyond what is needed for safety alone - are huge in terms of increased energy usage and carbon footprint. Ultra-pure water might not even be safe, adds Snyder.
The widespread occurrence of pharmaceuticals and endocrine disruptors reflects improved detection techniques, rather than greater pollution, says Snyder. Contamination is a fact of modern life, he adds.
"As we continue to populate and aggregate, our wastes will certainly accumulate where we live," he says. "We as a species have decided to live a modern life, with pharmaceuticals, plastics, transportation - therefore we must accept that there will be a certain degree of contamination."