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://water.epa.gov

Water Conditioning & Purification Magazine: http://www.wcponline.com

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