Twisp, WA Radon Levels

Q: What EPA Radon Zone is Twisp in?

Twisp is in Okanogan County, EPA Zone 1.

Q: How much does radon mitigation cost in Twisp?

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

Check local Twisp radon levels and find certified testing and mitigation professionals to keep your home safe

Twisp, WA Radon Facts

EPA Radon Zone Zone 1 — High Risk > 4.0 pCi/L (Zone 1)

County Okanogan County, WA

Zip Code 98856

Positioned in Okanogan County within Washington's North Cascades region, Twisp sits in a glacial valley where granitic bedrock and alluvial deposits typically produce lower radon levels. The town's housing includes both historic homes and newer mountain residences, many built on slab foundations due to the mountainous terrain. Although radon testing data for the 98856 area is currently sparse, residents should still test their homes as geological conditions can vary significantly even within small mountain communities.

Twisp, WA Radon Mitigation

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

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Radon FAQ for Twisp, WA

What EPA Radon Zone is Twisp in?

Twisp and the 98856 zip code are in Okanogan County, which has an EPA assigned Radon Zone of 1. A zone of 1 predicts an average indoor radon screening level greater than 4 pCi/L.

How much does radon mitigation cost in Twisp?

Radon mitigation in Twisp 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 Twisp?

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 Washington

Cities in Washington with the most user-submitted radon test data, ranked by number of submissions.

City	Avg User Radon Level	Submissions
Vancouver	6.56 pCi/L	9
Kent	3.50 pCi/L	6
Olympia	7.00 pCi/L	5
Seattle	5.25 pCi/L	4
Bellevue	3.75 pCi/L	4
Spokane	11.67 pCi/L	3
Camas	8.00 pCi/L	3
Centralia	7.00 pCi/L	3
Bellingham	4.50 pCi/L	2
Kirkland	4.50 pCi/L	2