Most countries don’t systematically follow drug residues in drinking water and there are also no maximum residue thresholds. In the USA, at least one contaminant was detected in seventy-five percent of the groundwater wells tested; in virtually all the streams and stream sediments tested; in about 80% of the estuarine sediments tested; in about 80% of the freshwater fish tested and in nearly all of the salt-water fish tested (H. John Heinz III Center 2008).
Of 62 big waterworks in the USA, only 28 had tested their water for drug residues by the mid 2000s. New York, Houston, Chicago and Miami had never tested their water. Those that do test find a disturbing reality. In Philadelphia 56 different drugs were found in the drinking water and 63 in the water source. In San Francisco’s drinking water there are sexual hormones, in Washington 6 different drugs (USA Today 2008). Purification of water to get rid of the drugs might cost in the range of 200 dollar per inhabitant and year (UNT 2008).
Among the human medications found in water in the USA are antidepressants, medications for high blood pressure and diabetes, anticonvulsants, steroid medications, oral contraceptives, hormone replacement therapy medications, codeine, non-prescription pain relievers, chemotherapy drugs, heart medications, and antibiotics (President’s Cancer Panel 2010).
Our drinking water doesn't only contain prescription drugs, but pesticides as well. In most countries there is no systematic follow up of pesticides in nature and in no country there is monitoring of all active substances; what is found is still frightening enough. Eighty percent of all rivers in the USA contain pesticide residues. Sixty percent of all wells have residues. The proportion contaminated wells was almost as high in urbanized areas, due to use in home gardens, gravel or stone paths, golf courses etc. In France, pesticides are found in all rivers and half of all water sources had at least traces of them. Of the fifty substances that are checked in the Netherlands, two thirds were found in ground water (OECD 2001). 20 pesticides were found in groundwater used by 3.5 million people in the Santa Ana River watershed. On the great plains in the USA researchers detected two insecticides and 27 herbicides in reservoir water. Water treatment removed from 14 to 86% of individual herbicides. Drinking water contained 3–15 herbicides (average, 6.4).