EPA has not established a maximum contaminant level for sulfate. On July 18, 2003 (68 FR 42897), the Agency announced its final determination that no regulatory action is appropriate or necessary for sulfate.
Sulfate in drinking water currently has a secondary maximum contaminant level (SMCL) of 250 milligrams per liter (mg/l), based on aesthetic effects (i.e., taste and odor). This regulation is not a federally enforceable standard, but is provided as a guideline for states and public water systems. EPA estimates that about 3% of the public drinking water systems in the country may have sulfate levels of 250 mg/l or greater. The Safe Drinking Water Act (SDWA), as amended in 1996 directs the EPA and the Centers for Disease Control and Prevention (CDC) to jointly conduct a study to establish a reliable dose-response relationship for the adverse human health effects from exposure to sulfate in drinking water, including the health effects that may be experienced by sensitive subpopulations (infants and travelers). SDWA specifies that the study be based on the best available peer-reviewed science and supporting studies, conducted in consultation with interested states, and completed in February 1999.
For more information on the regulatory determination for sulfate please visit our Web site at http://water.epa.gov/scitech/drinkingwater/dws/ccl/reg_determine1.cfm.