Radon Testing Requirements in South Dakota

By Chris, Founder of RadonResources.com · Reviewed against South Dakota statutes and state radon program guidance

South Dakota doesn’t require radon testing for homes, home sales or rentals. What state law does require is disclosure. Sellers of most homes must complete a property condition disclosure statement that asks whether they know of radon in the house or in well water and whether either has been tested. Testing is voluntary, but the state radon program recommends it, offers a limited number of free test kits each year and directs residents to nationally certified professionals. This article covers what South Dakota requires, what it doesn’t and how to test your home.

Is radon testing required in South Dakota?

No. We found no South Dakota law that requires homeowners, sellers, buyers, landlords or lenders to test for radon. The state’s approach relies on disclosure during home sales and on public education through the Department of Agriculture and Natural Resources (DANR) radon program.

That doesn’t mean radon is a minor issue in the state. The EPA places eastern South Dakota in Zone 1, its highest radon potential category, and the rest of the state in Zone 2. No part of South Dakota falls in Zone 3. Because radon levels vary from house to house, a test is the only way to know a specific home’s level. Our article on whether radon maps are useful or misleading explains why zone designations can’t stand in for a test.

What South Dakota requires when you sell a home

South Dakota law requires the seller of residential real property to give the buyer a completed property condition disclosure statement before the buyer makes a written offer. The requirement applies to properties with no more than four dwelling units in one structure. If a material fact changes after the form is delivered, the seller must give the buyer a written amendment before closing or possession, whichever comes first.

The current form from the South Dakota Department of Labor and Regulation, revised in July 2025, has a hazards section that asks whether the seller is aware of any existing hazardous conditions and whether any tests have been performed. Radon appears twice:

• Radon gas (house). The seller marks yes or no for whether they know of an existing radon condition, and yes or no for whether a test has been performed.
• Radon gas (well). The same two questions apply to radon in well water.

Each row includes space for comments, where a seller can note test results or a mitigation system. The form doesn’t require attaching a test report, and it doesn’t require the seller to test.

What the disclosure form doesn’t tell a buyer

The disclosure reflects only what the seller knows as of the date on the form. The form itself states that it is not a warranty of any kind and not a substitute for inspections that either party may want. A seller who has never tested can accurately answer “no” to both radon questions, which tells the buyer nothing about the home’s current level.

An older test can also be misleading. Radon changes with the season, the way a house is heated and changes to the foundation or living space. A test taken years ago, in summer or before a basement was finished may not reflect what the buyer will live with. Our guide to radon testing in winter vs. summer explains how timing affects results.

Rental properties and new construction

We found no South Dakota requirement for landlords to test rental units for radon or to disclose radon to tenants. South Dakota also doesn’t require radon-resistant construction in new homes statewide, according to a 2023 South Dakota Searchlight report. Some builders include radon-resistant features voluntarily, and a passive vent pipe can often be converted to an active system later if testing shows elevated levels. Our article on radon-resistant new construction covers how those features work.

Local rules can differ from state law, and rules change. If you’re building, buying or renting, check with your city or county building department and your real estate attorney about any local requirements.

How common elevated radon is in South Dakota

South Dakota is widely considered a high-radon state. The South Dakota Searchlight reported in 2023 that about 60 percent of tested homes in the state had elevated radon, with an average reading of 9.8 pCi/L, and that Custer County had the highest county average. Those figures come from homes that were tested, not a random sample of all homes, so they may not represent every household. They’re still consistent with the EPA’s Zone 1 and Zone 2 designations for the state.

South Dakota homeowners have submitted 31 radon readings to RadonResources.com, from places including Spearfish, Sioux Falls, Rapid City, Aberdeen and Watertown. Every one of them was at or above 4 pCi/L. That result reflects who chooses to share a reading, since people with high results are more likely to look for information. It can’t tell you your own level, but it shows that elevated readings turn up across the state. You can browse radon readings homeowners have reported or visit our South Dakota radon page for local professionals.

How to test your South Dakota home

DANR offers 500 free radon test kits to South Dakota residents each year through an online request form, while supplies last. You can also buy a test kit or hire a professional. The state program accepts both passive tests, which are mailed to a lab, and active monitors that give readings directly, as long as they meet EPA standards.

For a valid result, DANR’s guidance follows standard testing practice:

• Place the test in a frequently used room on the lowest livable level of the home.
• Keep it away from exterior walls, windows, drafts and nearby objects.
• Keep exterior windows and doors closed for at least 12 hours before the test and throughout it, except for normal entry and exit.

The EPA recommends fixing a home at or above 4 pCi/L and considering action between 2 and 4 pCi/L. No radon level is considered completely safe. Our radon testing guide walks through the process, our radon test kit comparison covers the options and our article on what 4.0 pCi/L actually means explains how to read a borderline result.

Testing during a home purchase

Because the disclosure only reports what the seller knows, many South Dakota buyers schedule a radon test during the inspection period. A short-term test fits a transaction timeline. Many buyers hire a certified measurement professional so the result is less likely to be disputed. If a test comes back high, buyers and sellers commonly negotiate a credit, a repair before closing or a holdback for mitigation. Our guide for real estate agents on radon covers how testing fits into a sale.

Testing well water

The disclosure form asks separately about radon in well water, which is a reminder that homes on private wells can have a second source. If your home uses a private well, consider testing both the air and the water.

Hiring a radon professional in South Dakota

South Dakota doesn’t run its own licensing program for radon testers or mitigators. DANR directs residents to professionals certified by the National Radon Proficiency Program (NRPP) or the National Radon Safety Board (NRSB). Without a state license to check, verifying national certification is the most reliable way to confirm a contractor has radon-specific training.

The most common fix for elevated radon is active soil depressurization, a vent pipe and fan system that draws radon from beneath the foundation and releases it above the roof. Sealing cracks helps a system work better, but sealing alone is usually not a dependable fix for significantly elevated radon. After installation, a post-mitigation test confirms whether the system lowered the level. Our guide to hiring a certified radon mitigator and our radon contractor checklist list the questions to ask before you hire.

Frequently asked questions

Do South Dakota sellers have to test for radon?

No. South Dakota requires sellers to complete a disclosure statement that asks whether they know of radon in the house or well water and whether tests have been performed. It doesn’t require a test. A seller who has never tested can answer “no,” so buyers who want a current number usually arrange their own test during the inspection period.

When does a South Dakota seller have to give the buyer the disclosure statement?

State law requires the seller to give the buyer the completed disclosure statement before the buyer makes a written offer. If the seller learns of a material change afterward, such as a new radon test result, they must provide a written amendment before closing or the date of possession, whichever comes first.

How do I get a free radon test kit in South Dakota?

The South Dakota Department of Agriculture and Natural Resources offers 500 free radon test kits to residents each year through a request form on its radon program website. Supplies are limited, so kits may run out. You can also call the DANR radon line at 1-800-438-3367 for help.

Does South Dakota require radon systems in new homes?

No statewide requirement exists for radon-resistant construction in new homes, based on available reporting. Some builders and local jurisdictions may include radon-resistant features. If you’re building or buying new construction, ask the builder whether a passive radon system was installed, and test the home after you move in.

Testing is your decision in South Dakota

South Dakota leaves radon testing to homeowners, buyers and renters. The law makes sure sellers share what they know, and the state helps with free kits and guidance, but no rule will prompt a test for you. Given how common elevated radon is in the state, a test is a reasonable step for any home. If you’d like help with testing or a high result, you can connect with a certified radon professional in South Dakota.

Sources and further reading

• South Dakota Department of Agriculture and Natural Resources, Radon Program (free test kits, testing guidance, radon zones, NRPP and NRSB professionals).
• South Dakota Codified Laws, Section 43-4-37, Section 43-4-38 and Section 43-4-44 (residential property definition, disclosure timing, disclosure statement).
• South Dakota Department of Labor and Regulation, Seller’s Property Condition Disclosure Statement, revised July 2025 (radon questions, no-warranty language).
• South Dakota Searchlight, Living in SD Means Elevated Risk for Radon Exposure, Lung Cancer (2023 test statistics, state law overview).
• U.S. Environmental Protection Agency, A Citizen’s Guide to Radon (action levels, testing guidance).
• RadonResources.com user-submitted radon readings (self-reported and not a representative sample).

This article is for general educational purposes and is not legal or medical advice. Laws and forms can change, and local rules may differ from state law. Consult a South Dakota real estate attorney for legal questions and a certified radon professional for testing or mitigation.