Water Quality

The U.S. Environmental Protection Agency sets standards for water that could affect human health and works with local government officials to reduce health risks in water where you swim or play.
Several of these trace elements are regulated by the EPA and are on their list of primary drinking water standards. These include arsenic, copper, and lead, as well as cadmium, chromium, mercury, and selenium.
Your water might be affected by iron, a commonly occurring constituent of drinking water. Iron tends to add a rusty, reddish brown (or sometimes yellow) color to water, and leaves particles of the same color.
A frequent cause of musty, earthy odors, especially toward the end of the summer, is naturally occurring organic compounds derived from the decay of plant material in lakes and reservoirs.
The U.S. Food and Drug Administration and States regulate bottled water.
Information is available through the Mercury Research in the USGS Web page. 
The best way to learn about your local drinking water quality is to read the annual drinking water quality report/consumer confidence report that water suppliers now send out by July 1 of each year.
The USGS Web site Water Resources of the United States can direct you to information about your local water body.
The best place for this sort of information is the National Climatic Data Center, which is part of the National Oceanic and Atmospheric Administration of the U.S. Department of Commerce.