The Source of Domestic Water

To understand the problems associated with water pollution, we need to look at the water that comes from each water source: water from wells, or ground water, and water from lakes, reservoirs and rivers or surface water.

Ground Water:
Buried from a few feet to a half mile or more beneath the earth's surface are strata known as aquifers (water-bearing layers of porous rock, sand, and gravel). The "ground water" in these aquifers was once believed to be beyond the reach of pollutants. But increasing quantities of synthetic chemicals and other harmful substances such as cleaning agents, salts used to melt ice and snow from highways, leaks from underground oil and gas tanks, agricultural chemicals, and surface water - are contaminating our subterranean water supplies. These materials filter down from the land surface into the aquifers or directly contaminate unprotected wells.

Surface Water
About half of the US population gets its drinking supply from surface water - that is, from rivers, creeks, lakes, streams, or reservoirs. Pollution of surface water can come from many sources. Air pollutants may enter surface water through rain. Chemical and other pollutants may be washed into surface water by rain or the action of humans. Finally we may pollute surface water intentionally by dumping home or industrial wastes.