Copper in California Drinking Water — 40 ZIPs Tested
EPA data analysis for copper in California drinking water systems
ZipCheckup tracks Copper in California drinking water: 40 ZIP codes with detected levels on record. 47 ZIP codes exceed the EPA limit (1.3 mg/L (action level)). Copper carries a moderate health-risk designation.
Copper Contamination in California
ZipCheckup analyzed drinking water data across 1,479 ZIP codes in California for copper. Copper appears in EPA records only as an action-level exceedance under the CU90 code (at or above the 1.3 mg/L action level), and the EPA transmits no verified copper concentration. 40 ZIP codes in California carry a copper action-level exceedance on record. A ZIP with no copper record has not been shown to be clean: absence means no exceedance was reported, not that copper is safe.
The violation rate for copper in California is 3.2% of all ZIP codes — roughly in line with the national average.
EPA Standard for Copper
The EPA maximum contaminant level (MCL) for copper is 1.3 mg/L (action level), governed by the Lead and Copper Rule. Water systems that exceed this limit must take corrective action and notify consumers.
Health Effects of Copper
Short-term exposure to copper above the action level causes gastrointestinal distress (nausea, vomiting, diarrhea). Long-term exposure can cause liver and kidney damage. People with Wilson's disease are particularly sensitive.
How to Remove Copper From Drinking Water
The most effective treatment for copper removal is Reverse Osmosis or NSF 53 Carbon Block. Look for filters certified under NSF 53 standards.
Check Your ZIP Code
Use the ZipCheckup water quality search to see copper data for your specific water system in California.
Cities with Copper Data in California
20 cities in California have copper testing data available.