A metallic taste can be caused by manganese, iron, zinc, or copper. These metals often discolor tap water and can stain plumbing fixtures and clothing. EPA has set non-enforceable secondary maximum contaminant levels for these contaminants that will prevent most aesthetic and cosmetic effects. EPA has set enforceable maximum contaminant levels for those contaminants that may cause adverse health effects (Secondary Drinking Water Regulations: Guidance for Nuisance Chemicals, EPA810-K-92-001; July 1992).
To help determine the cause(s) of aesthetic or cosmetic effects from your drinking water, contact your local drinking water system. Additional guidance for household well owners is available at http://water.epa.gov/drink/info/well/index.cfm. General information on nuisance chemicals is available at http://water.epa.gov/drink/contaminants/secondarystandards.cfm .