The Short Answer: Yes, When They’re Designed Right
You are right to be slightly skeptical about paying for a pipe and a fan when you cannot see or smell the gas they remove.
We understand this hesitation from property owners dealing with surprise test results. If you are wondering, “do radon mitigation systems work?”, the reality is that they absolutely do. Active soil depressurization is the exact mitigation method the EPA recommends for US homes.
Our radon mitigation installations routinely achieve a 90 to 95 percent reduction in harmful soil gas levels based on recent 2026 field data. Let’s look at the numbers, what they actually mean for your property, and walk through the specific factors that control your final result.
What Reduction Should You Expect?
Most well-installed systems bring a home safely below the EPA action level of 4.0 pCi/L. Many setups perform much better than that baseline.
Our data on radon mitigation effectiveness shows incredible success in Iowa, where the state average sits at an unusually high 8.5 pCi/L:
- Up to 98.9% reduction on homes we have mitigated.
- Homes above 4.0 pCi/L routinely brought below 1.0 pCi/L.
- Results confirmed by a post-mitigation test on every single system.
- Over 71 percent of local houses test above the EPA threshold before treatment.
| Starting level | To reach 4.0 | To reach 2.0 | To reach 1.0 |
|---|---|---|---|
| 6 pCi/L | 33% reduction | 67% reduction | 83% reduction |
| 10 pCi/L | 60% reduction | 80% reduction | 90% reduction |
| 20 pCi/L | 80% reduction | 90% reduction | 95% reduction |
| 40 pCi/L | 90% reduction | 95% reduction | 97.5% reduction |
A good system isn’t aiming to just squeak under 4.0 pCi/L. It aims as low as the foundation allows.
Why we aim below 1.0
The EPA action level is just a minimum, and there is no known safe level of radon exposure. Getting below 1.0 pCi/L gives you a wide safety margin through harsh Iowa winters, when levels tend to run highest. The World Health Organization actually recommends a stricter 2.7 pCi/L reference level, making lower targets even more important.
What Limits Results?
Radon extraction setups are never one-size-fits-all. These specific building factors dictate exactly how low a home can go.
Soil under the slab
Clean gravel under a slab lets suction spread easily across the entire footprint. Tight clay or a slab poured directly on dirt severely slows air movement.
We often perform a pressure field extension test to measure this exact airflow before drilling. Those tighter soils require a modified approach. Houses built on dirt or clay may need a larger suction pit, an upgraded motor, or a second suction point to achieve proper depressurization.
Foundation type
A single basement slab is the simplest layout to treat. Complex layouts require dedicated suction on each distinct area, including:
- Split-level homes with staggered floors.
- Room additions poured on separate concrete slabs.
- Dirt or gravel crawlspaces requiring polyethylene vapor barriers.
We design complex networks of piping to connect these isolated sections. Missing even one small slab section can leave ambient gas levels high. This is a common issue in walkout basements where the front and back of the house sit at different elevations.
Sumps and openings
An open sump pit pulls basement air right into the piping and drastically weakens soil suction. Large floor cracks, open block walls, and untreated floor drains can cause that same pressure loss.
We seal these vulnerable pits with heavy-duty, airtight polycarbonate domes. Sealing these gaps forces the fan to pull gas from the soil rather than conditioned air from your living room. A tightly sealed basement is critical for home energy efficiency as well.
Fan size
A fan that is too small for the soil and footprint will not pull enough suction to work. A fan that is completely oversized wastes electricity and creates annoying structural vibrations.
We strictly match the motor size to the specific resistance of your foundation. Leading US manufacturers like Fantech and RadonAway produce specialized units for different environments. The Fantech Rn2, for example, offers great energy efficiency for standard gravel sub-grades.
Well water
If your rural property utilizes a private well, some radioactive gas can actually enter through the water supply itself. A standard soil-gas depressurization pipe will not fix an aquatic source. Our technicians always evaluate this alternate pathway during rural property inspections. Please see radon in well water for detailed treatment options.
How a Post-Mitigation Test Proves It
You should never just take a contractor’s word for the final result. After the equipment has run long enough to stabilize, a post-mitigation test measures the exact new concentration.
We supply continuous radon monitors or AARST-approved testing kits to accurately verify the drop. Compare this new measurement directly to your original result and to the 4.0 pCi/L action level. That final number provides your verifiable proof of safety. Read more about post-mitigation testing.
After passing that initial check, the U-tube manometer on your pipe becomes your day-to-day visual monitor. If the red or blue liquid inside stays uneven, the fan is actively pulling suction. We recommend retesting the property every two years to confirm the equipment is still doing its job.
What If Levels Stay High?
It happens occasionally during complex installations. A missed slab section, an unsealed plumbing block-out, or a hidden soil pathway can keep indoor readings stubbornly elevated.
We rely on diagnostic testing to pinpoint exactly where the system is losing pressure. The proper professional fix is to diagnose the structural flaw and adjust the equipment:
- Check that the U-tube manometer gauge shows adequate vacuum pressure.
- Look for isolated sections of the foundation the vacuum field is not reaching.
- Add a secondary suction point, upsize the fan motor, or seal the missed entry route.
- Retest the property under closed-house conditions.
A common mistake DIYers make is simply swapping in a larger fan without addressing unsealed joints. This just increases noise and electric bills without solving the core airflow issue. Our professional installations all carry a comprehensive 5-year warranty against structural defects. If your radon is still high after mitigation, the team adjusts the hardware at no extra charge.
Signs of a Well-Designed System
A quality installation looks clean, sounds quiet, and follows strict national safety codes. Look for these specific visual indicators on your property:
- A suction point placed exactly where the pressure field reaches the entire slab.
- Sealed pipe joints and a fully caulked slab penetration using polyurethane.
- A fan mounted completely outside the living space, discharging exhaust at least 12 inches above the roofline.
- A sealed, airtight lid if the house features a basement sump pump.
- A clearly labeled U-tube manometer gauge you can easily read.
- A documented post-mitigation test filed with your project paperwork.
If you have a high test result and want to know the specific radon reduction percentage realistic for your layout, send the report and a few basement photos. We provide a customized system plan and a flat-rate price through a free virtual estimate. If you are still asking yourself “do radon mitigation systems work?”, taking action today is the fastest way to secure safe, breathable indoor air.