You're not alone if you're concerned about the water you and your family drink. A survey by the Water Quality Association found that three-quarters of Americans don't believe their household water supply is as safe as it could be. In a recent USA Today/CNN/Gallup Poll, 47 percent of respondents reported they won't drink water straight from the tap.

Environmental problems have an enormous impact on water quality. Water runoff from industrial plants and farms, acid rain and other forms of pollution have tainted groundwater and surface water supplies in many areas of the world. Population growth, urban and suburban sprawl, and industrial and agricultural expansion continue to stress fresh water supplies