Contaminant Occurrence Map

The new Contaminant Occurrence Map displays data in the United States for regulated drinking water contaminants that have an enforceable level (MCL or Action Level) above the health-based goal level (MCLG) and also aesthetic contaminants that can cause taste, odor and color or staining issues.

• ​The Contaminant Occurrence data collection effort gathered water quality data over the last 10 years for 57 different drinking water contaminants in the United States. 
• The data comes from 46 state regulatory agencies, the US EPA’s 4th Unregulated Contaminant Monitoring Rule (UCMR4) and the EPA’s Safe Drinking Water Information System (SDWIS). 
• The mapping tool provides a visual illustration of this occurrence data provided by the states and through US EPA UCMR4. 
• ​This map shows statistical summaries of all data, not regulatory compliance.