Well actually actually a while back I remember reading sources of drinking water contain minute traces of pharmaceuticals...I believe it goes like this:
1- pharms consumed by humans
2-then excreted in the form of feces
3-delivered into to sewer where it flows to treatment plant
4-waste treated at plant to within safe tolerations of being released in local bodies of water/rivers..
5-water then leaches into surrounding ground/aquafers then returns via municipal wells where is treated
6-then is pumped back to the population
The article claimed that the traces of pharms were safe&that no ill effects to be felt by population.. I live in Indianapolis&such is the case with our water supplies...and it seemed as the majority of pharms found in the water were a % of anti-depressants along with others...