Here are a few websites that will provide information for you.

USEPA Drinking Water Contaminants at http://www.epa.gov/ogwdw/hfacts.html

CA Department of Public Health Drinking Water Program at: www.cdph.ca.gov/programs/Pages/DWP.ASPX

CA Departmet of Public Health Drinking Water Regulations at: www.cdph.ca.gov/services/DPOPP/regs/Pages/def

American Water Works Association at: www.awwa.org

American Water Works Association Research Foundation at: www.awwarf.org

Center for Desease Control and Prevention at: http://www.cdc.gov/nceh/ehhe/water/