Copper in California Drinking Water — 165 ZIPs Tested

Copper Contamination in California

ZipCheckup analyzed drinking water data across 2,630 ZIP codes in California for copper contamination. 165 ZIP codes have reported copper detections, and 76 have EPA violations on record.

The violation rate for copper in California is 2.9% 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.

Worst ZIP Codes for Copper in California

These ZIP codes reported the highest copper levels in California based on CCR reports and EPA data:

Lowest Copper Levels in California

These ZIP codes had the lowest reported copper detections in California:

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.