If you rely on a public water system in Castro Valley, California, Copper is a contaminant your utility has been required to test for — and EPA records show it has been detected at measurable levels, making it worth understanding as part of your tap water's detection record.

Data: EPA SDWIS, CCR Reports, ECHO Last verified: 2026-04-05

Copper in Castro Valley Tap Water

Copper has been detected in Castro Valley, California drinking water at a maximum level of 2250 ppb — 1.73x the EPA action level.

This analysis covers 60,207 residents across 2 ZIP codes in Castro Valley.

Castro Valley's overall water quality grade is B (77/100).

Is Copper in Castro Valley Water Safe?

If you live in an affected ZIP code, consider installing a reverse osmosis or nsf 53 carbon block filter certified under NSF 53 and testing your water independently.

Copper Levels by ZIP Code

Average copper level across Castro Valley: 2250 ppb

Health Effects of Copper

• Nausea, vomiting, and diarrhea (short-term, high levels)
• Liver and kidney damage (long-term)
• Particularly dangerous for people with Wilson's disease
• Infants are more sensitive than adults

Health risk severity: Moderate. Governed by the Lead and Copper Rule.

How Copper Gets Into Drinking Water

• Corrosion of copper household plumbing
• Acidic (low pH) water accelerates copper leaching
• New copper pipes leach more than aged ones
• Mining and industrial discharge (rare for tap water)

What to Do About Copper in Castro Valley Water

1. Run water for 30-60 seconds before use (flushes stagnant water)
2. Install an NSF 53 or NSF 58 certified filter
3. If pH is low, consider a whole-home acid neutralizer
4. Test first-draw morning water to check actual copper levels

Look for filters certified under NSF 53 for copper removal.

Related

• Copper — National Overview
• California Water Quality
• Castro Valley Water Quality
• Check Your ZIP Code