Some public water systems have already begun initial monitoring. The original Safe Drinking Water Act was passed by Congress in 1974, and EPA began setting national standards in 1975. EPA believes that the economic impact of this proposal on most water treatment systems and their customers will be small. EPA estimates that less than one-percent of the nation's drinking water systems will have to install new treatment equipment to meet today's requirements. A standard for sulfate, once included among the package of standards, has been deferred for additional consideration.
Sulfate causes diarrhea in un-acclimated people, primarily travelers and newborns.
Most people are believed to acclimate to sulfate in a short time and it has no known long-term effects. Sulfate treatment is expensive, especially for small systems in small towns where sulfate is prevalent. During the deferral, EPA will explore innovative approaches to make compliance more affordable for small systems while still protecting health. EPA will also issue a health advisory identifying sulfate levels that may cause diarrhea. EPA standards generally apply to any drinking water supply system that regularly serves at least 25 people.