There is a thought provoking review in BMJ vol 337, 12th July p 80-81 which discusses the pollution of our UK drinking water with drugs which have been excreted in the urine and eventually pass into the domestic water system.
Stringent precautions are taken to remove pesticides and other major pollutants but drugs because of their chemistry may pass through.
The list of such drugs downstream of a major conurbation is likely to be considerable. Other than cytotoxic drugs and antibiotics, albeit in microscopic amounts there will be traces of the oral contraceptive components. Combinations of drugs will be additive in their effects and there is particular concern for the foetus.
On the other hand plant secondary metabolites will also pass into the domestic water and may have beneficial effects when present.
When one drinks cold refreshing water from a country or mountain stream look upstream at the cattle and wild animals who also use the streams.
Watts 2008 How clean is your water ? BMJ vol 337 pp 80-82
- Martin Eastwood