US Wastewater Treatment Plant Directory

Name: US wastewater treatment plant directory
Creator: Klarifi
License: https://klarifi.io/terms-of-service

11,783 publicly owned treatment works treating 14,938 MGD for about 144,666,621 residents, including 5,662 lagoon systems. Flow, NPDES permits, treatment technology and three-year compliance for each, built from public EPA data and enriched by Klarifi.

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Sources and methodology

Flow, permit and violation figures come from the EPA's ICIS-NPDES discharge monitoring records. Population served comes from the Clean Watersheds Needs Survey 2022. Treatment structures are identified by Klarifi's review of aerial imagery, and capital improvement projects are extracted from published municipal budget documents. Violations are counted over the last three years of monitoring reports.

Data refreshed September 11, 2026.

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