what could be a possible source of sulfates found in a supply of drinking water?

Answer 1

Some rocks and even some soils contain sulfites; as the water runs over (and through) these, it picks up some of the sulfates.

Answer 2

OOPS - I meant of course "SULFATES" (not sulfites.)

Answer 3

Certain industrial wastes can also supply sulfates to our water, as does rain.

Answer 4

thanks!