Williams, CA Radon Mitigation and Testing

Q: What EPA Radon Zone is Williams in?

Williams is in Colusa County, EPA Zone 3.

Q: How much does radon mitigation cost in Williams?

Radon mitigation typically costs between $800 and $2,000. Most standard systems fall in the $1,000-$1,500 range.

Colusa County

EPA Zone 3

Set in Colusa County within California's Sacramento Valley, Williams sits where alluvial deposits from the Coast Range create relatively low radon potential in EPA Zone 3. Testing submissions for this 95987 agricultural community remain limited, emphasizing the value of home-specific testing. While the valley's sedimentary geology typically produces modest radon levels, individual properties can still vary based on construction characteristics and local soil conditions.

Williams, CA Radon Mitigation

Professional radon mitigation is the most effective way to permanently lower radon levels and protect your household.

Williams, CA Radon Testing

Finding qualified radon testing professionals is the first step toward protecting your home.

Williams Radon Facts

Key details about the radon risk profile for Williams and the 95987 zip code area.

EPA Radon Zone

Zone 3 — Low Risk

County

Colusa County, CA

Zip Code

95987

Predicted Screening Level

< 2.0 pCi/L (Zone 3)

Williams and the 95987 zip code are located in Colusa County, which has an EPA assigned Radon Zone of 3. A radon zone of 3 predicts an average indoor radon screening level less than 2 pCi/L. The EPA recommends testing every home regardless of zone classification.

Radon FAQ for Williams, CA

What EPA Radon Zone is Williams in?

Williams and the 95987 zip code are in Colusa County, which has an EPA assigned Radon Zone of 3. A zone of 3 predicts an average indoor radon screening level less than 2 pCi/L.

How much does radon mitigation cost in Williams?

Radon mitigation in Williams typically costs between $800 and $2,000. Most homes with standard basements can be mitigated with a sub-slab depressurization system in the $1,000–$1,500 range. Factors that can increase cost include complex foundations, crawl spaces, or very high radon levels.

Should I test for radon if I'm buying a home in Williams?

Yes. Radon testing should be part of every home purchase. A short-term radon test is typically included as part of the home inspection process and costs $150–$250. If elevated levels are found, you can negotiate mitigation as part of the sale.

Most Active Radon Markets in California

Cities with the most user-submitted radon test data in the state.

City	Avg User Radon Level	Submissions
Los Angeles	7.83 pCi/L	6
Mammoth Lakes	10.80 pCi/L	5
San Jose	4.20 pCi/L	5
Rancho Palos Verdes	8.00 pCi/L	4
Woodland Hills	7.67 pCi/L	3
South Lake Tahoe	6.33 pCi/L	3
Palos Verdes Peninsula	6.00 pCi/L	3
Bishop	5.67 pCi/L	3
Sacramento	4.33 pCi/L	3
Oakland	3.33 pCi/L	3
Fresno	10.00 pCi/L	2
Davis	8.00 pCi/L	2
Palo Alto	6.50 pCi/L	2
Studio City	6.50 pCi/L	2
Menlo Park	5.00 pCi/L	2
Truckee	5.00 pCi/L	2
Walnut Creek	4.00 pCi/L	2
San Diego	3.50 pCi/L	2
San Francisco	3.50 pCi/L	2
Belmont	20.00 pCi/L	1