According to the  USEPA (U.S. Environmental Protection Agency)

 

The sources of drinking water--both tap water and bottled water--include rivers, lakes, streams, ponds, reservoirs, springs and wells.  As water travels over the surface of the land or through the ground, it dissolves naturally occurring minerals and, in some cases, radioactive material, and can pick up substances resulting from the presence of animals or from human activity.  Contaminants that may be present in source water include:

 

 Microbial contaminants such as viruses, bacteria and protozoa such as Cryptosporidium, that may come from sewage treatment plants, septic systems, agricultural livestock operations and wildlife.

* Inorganic contaminants such as salts and metals naturally occurring or resulting from urban storm water runoff, industrial or domestic wastewater discharges, oil and gas production, mining and farming.

* Synthetic organic contaminants such as pesticides and herbicides that may come from a variety of sources, including agriculture, urban storm water and residential uses.

* Volatile organic contaminants from industrial processes and petroleum production, and from gas stations, urban storm water runoff, agricultural application and septic systems.

* Radio active contaminants that can be naturally occurring or be the result of oil and gas production, and mining actitivities.

 

Most of these contaminants can be filtered out of our water using the MultiPure solid carbon block water filter.  I have been using and recommending these filters for years and still believe they are the best in the market.  Click on the MultiPure link to the right for more information.