Yes. Sioux Falls buyers should test the home for radon unless a reliable recent test is available. Radon is invisible, levels can vary from one house to the next, and a neighborhood average cannot determine a specific home’s result.

The EPA radon guidance explains testing and the federal action level. South Dakota’s radon program provides state information and resources. Follow the test instructions and use a qualified professional when the contract deadline or testing conditions require it.

Mitigation cost depends on the home design and system required. Obtain a written proposal from a qualified mitigation provider and plan for a post-mitigation test.

Now the part that actually protects your wallet. Because you tested inside your inspection contingency, a high result is a negotiation, not a surprise you eat after closing. You can ask the seller to install a mitigation system before closing, credit you the cost at the table so you handle it yourself, or reduce the price. Which route makes sense depends on the market and how the rest of your deal is shaped, but the point is you have a seat at that table.

Keep in mind South Dakota’s disclosure rule here. Sellers are required to share known radon information on the Seller’s Property Condition Disclosure Statement (SDCL 43-4-44). If a prior test or an existing system shows up on that form, read it closely. But a disclosure is not a substitute for your own current test — an old reading or a blank line tells you nothing about the air in that basement today.

New construction deserves its own note. Some newer homes in the Tea, Harrisburg, and NW Sioux Falls corridor are built with a passive radon system — pipes roughed into the foundation that vent soil gas without a fan. Passive systems cut levels by roughly half, which isn’t always enough. If you’re buying new, still test after the home is finished, and budget for adding an active fan if the result comes back above 4.0. My guide on whether you need a Realtor for new construction in Sioux Falls covers how to get these details written into your builder agreement before you’re locked in.

FAQ

Is radon testing required when buying a home in South Dakota?
No. South Dakota has no law requiring a radon test or radon-resistant construction. The only rule is that sellers must disclose known radon information on the Seller’s Property Condition Disclosure Statement. Given that Sioux Falls sits in EPA Zone 1, you should test regardless — the state won’t do it for you.

What is a safe radon level in Sioux Falls?
The EPA recommends taking action at 4.0 pCi/L or higher. No level is completely risk-free, and the EPA suggests considering a fix even between 2.0 and 4.0. Below 4.0, most buyers don’t mitigate. With a Sioux Falls average near 6.0, plenty of homes here land above the action line.

How much does radon mitigation cost?

Mitigation pricing depends on the foundation, layout, system design and contractor. Get a written proposal from a qualified professional and retest after installation.

Can I ask the seller to pay for radon mitigation?
Yes. As long as you test inside your inspection contingency, you can negotiate for the seller to install a system, credit you the cost at closing, or lower the price. This is a normal ask in South Dakota deals, not a deal-breaker.

Do new construction homes in Tea and Harrisburg have radon?
They can. Some newer builds include a passive radon system that cuts levels by about half, but that’s not always enough to get below 4.0. Test after the home is finished and budget for an active fan upgrade if needed.

Ready to Buy With Your Eyes Open?

Radon is a small line item that catches a lot of Sioux Falls buyers off guard — and it’s one of the easiest things to handle when you plan for it before you write the offer. Get it tested, know your number, and use your inspection window while it’s open.

If you’re getting ready to buy in Sioux Falls, Brandon, Harrisburg, Tea, or anywhere in the metro and you want someone who’ll make sure details like this don’t slip, let’s talk. Call or text me at 605-201-2846, or start at siouxfallsgreathomes.com.

About Jeff Merrill: Jeff Merrill leads The Jeff Merrill Team, powered by eXp Realty, serving Sioux Falls and the surrounding South Dakota communities of Brandon, Harrisburg, Tea, Madison, Mitchell, Canistota, and beyond. Jeff coaches buyers, sellers, and new agents through the real decisions that shape a deal — no hype, no hedging. Reach him at 605-201-2846.