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Water quality · California

Water quality in California

Water quality (EPA SDWIS) data for ZIP codes in California. Pick a ZIP below to dive into the water quality summary.

Last verified 2026-04-25 · methodology

What lands here

Pages show the CWS serving the address, any health-based violations in the last 3 years, most recent lead and copper sampling result, and a link to the primary SDWIS record.

Source & refresh

EPA SDWIS. Refreshed quarterly (federal mandate). Primary source →

20 California ZIPs