California Department of Water Resources: http://wwwdwr.water.ca.gov

Natural Resources Defense Council: http://www.nrdc.org

NSF: http://www.nsf.org

Pacific Water Quality Association: http://www.pwqa.org

U.S. Environmental Protection Agency -- Office of Water: http://www.epa.gov/OW

Water Conditioning & Purification International: http://www.wcp.net

Water Quality Association: http://www.WQA.org