Radium exposure in drinking water is tracked by EPA across the country; households in Paso Robles, California are among those with confirmed detections in the public water record.

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

Radium in Paso Robles Tap Water

Radium has been detected in Paso Robles, California drinking water at a maximum level of 9.8 pCi/L — 1.96x the EPA MCL.

This analysis covers 35,658 residents across 2 ZIP codes in Paso Robles.

Paso Robles's overall water quality grade is D (50/100).

Is Radium in Paso Robles Water Safe?

Radium was detected in Paso Robles 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 Paso Robles: 9.8 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 Paso Robles 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
• Paso Robles Water Quality
• Check Your ZIP Code