Across Wilmington, California, federal monitoring data has captured Radium in water samples at detectable concentrations in the most recent available reporting cycle.

Data: EPA SDWIS, CCR Reports, ECHO Last verified: 2026-05-14

Radium in Wilmington Tap Water

Radium has been detected in Wilmington, California drinking water at a maximum level of 8 pCi/L — 1.6x the EPA MCL.

This analysis covers 3,875,566 residents across 2 ZIP codes in Wilmington.

Wilmington's overall water quality grade is C (58/100).

Is Radium in Wilmington Water Safe?

Radium was detected in Wilmington water but currently falls within EPA limits. However, some health organizations argue the EPA MCL may not be protective enough.

If you are concerned, a reverse osmosis or ion exchange filter can reduce radium levels further.

Radium Levels by ZIP Code

Average radium level across Wilmington: 8 pCi/L

Health Effects of Radium

• Increased risk of bone cancer (radium accumulates in bones)
• The body treats radium like calcium, storing it in bones
• Lifetime cancer risk of ~1 in 10,000 at 5 pCi/L
• No safe threshold for radioactive contamination

Health risk severity: High. Governed by the Radionuclides Rule.

How Radium Gets Into Drinking Water

• Natural radioactive decay in underground rock formations
• Groundwater sources (especially deep wells)
• Mining and industrial waste
• Higher in regions with specific geology (Midwest, parts of South)

What to Do About Radium in Wilmington Water

1. Reverse osmosis (NSF 58 certified) removes 90%+ of radium
2. Ion exchange (water softeners) can reduce radium
3. Point-of-use RO at kitchen tap is most cost-effective
4. GAC filters alone are NOT effective for radium

Look for filters certified under NSF 58 for radium removal.

Related

• Radium — National Overview
• Radium in California
• California Water Quality
• Wilmington Water Quality
• Check Your ZIP Code