Routine testing in Seminole, Oklahoma turned up Radium — samples from the public supply came back positive, placing this contaminant on the list of substances residents here have a concrete reason to look into.

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

Radium in Seminole Tap Water

Radium has been detected in Seminole, Oklahoma drinking water at a maximum level of 3.32 pCi/L — below the EPA MCL of 5 pCi/L (combined Ra-226 + Ra-228).

This analysis covers 6,899 residents across 2 ZIP codes in Seminole.

Seminole's overall water quality grade is A (93/100).

Is Radium in Seminole Water Safe?

Radium was detected in Seminole 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 Seminole: 3.32 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 Seminole 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 Oklahoma
• Oklahoma Water Quality
• Seminole Water Quality
• Check Your ZIP Code