Frequently Asked Questions

Where does the data come from?

All data comes from EPA’s Safe Drinking Water Information System (SDWIS), the official federal database of public water system violations.

What is a health-based violation?

A health-based violation means a contaminant was detected above the Maximum Contaminant Level (MCL) set by EPA, or a required treatment technique was not followed. These are the most serious violations.

What is a major violation?

EPA classifies some violations as “major” based on their severity and public health impact. Major violations trigger more aggressive enforcement actions.

How do I find my water system?

Search by your state and city. Most residents are served by a Community Water System (CWS). Your water bill should show the system name or PWSID number.

How often is data updated?

Data is cached for 1 hour. EPA updates SDWIS continuously as violations are reported and resolved.

Is this free?

Yes. Always. No account required.