Drinking Water Contaminants

The EPA regulates over 90 contaminants in public drinking water under the Safe Drinking Water Act. For each contaminant, the EPA sets a Maximum Contaminant Level (MCL) -- the highest concentration legally allowed in public water systems -- and a Maximum Contaminant Level Goal (MCLG), the level at which no known health effects occur. Below are the most important contaminants to understand as a homeowner, including how they enter your water, their health effects, and what you can do about them.