Suddenly, expensive bottled water doesn’t seem like such a waste of money. A study of public water supplies across the country, says the Associated Press, has found widespread contamination with over-the-counter and prescription drugs such as painkillers, tranquilizers, stimulants, anti-psychotics, and antibiotics. When people take medications, they excrete small quantities in urine and feces. The wastewater is treated, but sewage treatment plants don’t test for or try to eliminate specific drugs. So the “clean” water discharged into rivers, lakes, and groundwater contains small amounts of common medications, and it makes its way into reservoirs. Drugs have been detected in the water supplies of 24 major metropolitan areas, including Detroit, Philadelphia, and Louisville, and in Southern California and northern New Jersey. In some cases, 56 different pharmaceuticals were found in a single city’s drinking water. The doses are minuscule, in the parts per billion or trillion—far too small to produce noticeable effects—but the long-term health consequences of taking tiny doses of other people’s medications over decades are unknown. “We recognize it as a growing problem,” said Benjamin Grumbles of the federal Environmental Protection Agency, “and we’re taking it very seriously.”