Wilmington, DE Radon Mitigation and Testing

Q: What is the average radon level in Wilmington, DE?

Based on 4 user-submitted tests, the average radon level is 5.50 pCi/L.

Q: What EPA Radon Zone is Wilmington in?

Wilmington is in New Castle County, EPA Zone 2.

Q: How much does radon mitigation cost in Wilmington?

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

Avg: 5.50 pCi/L

New Castle County

EPA Zone 2

4 user tests

Delaware's largest city in New Castle County shows elevated radon levels with an average of 5.5 pCi/L that exceeds the EPA action threshold across multiple zip codes. Positioned within the Philadelphia metro area on Piedmont geology where crystalline bedrock meets coastal plain sediments, Wilmington's varied terrain creates conditions that can produce significant radon concentrations. The city's diverse housing stock, from historic rowhouses to modern developments, requires comprehensive testing given these consistently elevated readings throughout the metropolitan area.

5.50

pCi/L average

Above EPA Action Level

Based on 4 user-submitted radon tests for homes in Wilmington, DE. The EPA recommends taking action at or above 4.0 pCi/L.

4.0 EPA

10+

Wilmington, DE Radon Mitigation

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

Wilmington, DE Radon Testing

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

Wilmington, Delaware Radon Levels

User-submitted radon test readings from homes in the Wilmington area.

Radon Level	City	Home Age	Foundation	Submitted
6 pCi/L	Wilmington, DE	51-99 Years	Full Basement	Aug 2024
6 pCi/L	Wilmington, DE	21-50 Years	Full Basement	Sep 2023
7 pCi/L	Wilmington, DE	51-99 Years	Partial Basement	Apr 2019
3 pCi/L	Wilmington, DE	21-50 Years	Full Basement	Nov 2018

Have a radon test result for Wilmington? Submit your reading to help other homeowners.

Wilmington Radon Facts

Key details about the radon risk profile for Wilmington and the 19801 zip code area.

EPA Radon Zone

Zone 2 — Moderate Risk

County

New Castle County, DE

Zip Code

19801

Predicted Screening Level

2–4 pCi/L (Zone 2)

Avg. User Submitted Level

5.50 pCi/L

User Tests Submitted

Wilmington and the 19801 zip code are located in New Castle County, which has an EPA assigned Radon Zone of 2. A radon zone of 2 predicts an average indoor radon screening level between 2 and 4 pCi/L. The EPA recommends testing every home regardless of zone classification.

Radon FAQ for Wilmington, DE

What is the average radon level in Wilmington, DE?

Based on 4 user-submitted tests, the average radon level in Wilmington is 5.50 pCi/L. This exceeds the EPA's recommended action level of 4.0 pCi/L, and radon testing is recommended for all homes in the area.

What EPA Radon Zone is Wilmington in?

Wilmington and the 19801 zip code are in New Castle County, which has an EPA assigned Radon Zone of 2. A zone of 2 predicts an average indoor radon screening level between 2 and 4 pCi/L.

How much does radon mitigation cost in Wilmington?

Radon mitigation in Wilmington 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 Wilmington?

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 Delaware

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

City	Avg User Radon Level	Submissions
Middletown	7.43 pCi/L	7
Wilmington	5.50 pCi/L	4
Lewes	6.00 pCi/L	1
New Castle	4.00 pCi/L	1
Newark	No submissions	0