In towns and cities, what is the major cause of drinking water source pollution?
Plain Talk answer:
The major source of pollution is rainwater that flows into street catch basins (called urban runoff or stormwater runoff). While this rainwater alone is not necessarily harmful, it can pick up untreated waste products from our streets and yards, then dump it directly into rivers, streams and lakes (drinking water sources).
For more information on this and many other water-related topics, check out Plain Talk About Drinking Water
by Dr. James M. Symons.