Radon, PFOA, and PFOS are present in Harris County groundwater and well owners should know about them. PFOA and PFOS exceed EPA health standards, and radon levels are high enough to be a concern.
Radon comes naturally from the breakdown of uranium in the crystalline bedrock beneath the county. PFOA and PFOS are human-made chemicals that enter groundwater from contamination sources on the land surface, such as industrial sites, military installations, or places where firefighting foam was used. These chemicals travel down through soil and rock into the water your well draws from.
Groundwater in Harris County is soft and low in minerals overall, with very low sodium and sulfate. The crystalline bedrock that fills this region does not dissolve easily into water the way softer rocks like limestone do, which means fewer minerals end up in the water. Most wells in the county share this soft-water character.
Wells in Harris County have been found to contain PFOA, PFOS, and radon at levels above EPA health standards. PFOA and PFOS are chemicals that can build up in your body over time and have been linked to health problems including liver damage, thyroid disease, and immune system effects. Radon is a radioactive gas that enters water from soil and rock, and drinking water with radon increases your risk of stomach cancer and lung cancer from inhaled radon gas released during water use.
The good news is that Harris County wells generally have soft water with low sodium and sulfate levels. This means you are unlikely to see staining, scaling on fixtures, or the metallic taste and odor problems that come with harder water. Your appliances should not face the wear and tear from mineral buildup that affects many other areas.
We recommend testing your well for PFOA, PFOS, and radon as soon as possible since multiple contaminants exceed EPA standards in the county. Every well is different, and your water may have higher or lower levels than average. A comprehensive testing panel costs between two hundred and four hundred dollars and is the only way to know exactly what is in your water so you can treat it properly. Activated carbon filters and radon aeration systems can help address these specific contaminants.
Not sure if your well is affected? Get certified results in 5–7 days.
Test Your Well Water with Tap Score →| Contaminant | Samples ⓘ | % Above MCL ⓘ | Distribution ⓘ | Confidence ⓘ | Risk ⓘ |
|---|---|---|---|---|---|
| Radon | 1 | 100% | Low | High ⓘ | |
| PFOS ⓘ municipal | 10 | 80% | Low | High | |
| PFOA ⓘ municipal | 10 | 70% | Low | High | |
| Chloride | 4 | 0% | Low | Low ⓘ | |
| Iron | 1 | 0% | Low | Safe ⓘ | |
| Arsenic | 1 | 0% | Low | Low ⓘ | |
| Fluoride | 4 | 0% | Low | Low ⓘ | |
| HFPO-DA (GenX) ⓘ municipal | 10 | 0% | Low | Safe | |
| Nitrite | 1 | 0% | Low | Safe ⓘ | |
| PFNA ⓘ municipal | 10 | 0% | Low | Safe | |
| Nitrite | 1 | 0% | Low | Safe ⓘ | |
| HFPO-DA (GenX) ⓘ municipal | 10 | 0% | Low | Safe | |
| Fluoride | 4 | 0% | Low | Low ⓘ | |
| Iron | 1 | 0% | Low | Safe ⓘ | |
| PFNA ⓘ municipal | 10 | 0% | Low | Safe | |
| Lead | 1 | 0% | Low | Low ⓘ | |
| Manganese | 1 | 0% | Low | Safe ⓘ | |
| Nitrate | 4 | 0% | Low | Low ⓘ | |
| PFHxS ⓘ municipal | 10 | 0% | Low | Safe | |
| Sulfate | 4 | 0% | Low | Low ⓘ | |
| Uranium | 1 | 0% | Low | Low ⓘ | |
| Hardness | 4 | — | Low | Low ⓘ | |
| PFBS ⓘ municipal | 10 | — | Low | Low | |
| Sodium | 4 | — | Low | Low ⓘ | |
| pH | 4 | — | Low | Low ⓘ |
MCL = Maximum Contaminant Level (EPA limit for public water; used as benchmark for private wells). Distribution shows % of sampled wells in each concentration band. Methodology.
* Microbial contaminants (E. coli, coliform) reflect only samples from the last 10 years.
Data shows potential risk — a certified test confirms whether your water is affected.
Order a Tap Score Test →Population-level CDC data. Not individual risk prediction.
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