Groundwater in Harris County contains arsenic, radon, chloride, fluoride, uranium, nitrate, and PFOS compounds that well owners should know about. Many of these contaminants exceed EPA health standards, making them a serious concern for private well owners.
These contaminants come from two main sources: natural minerals released from the coastal plain rocks and sediments below, and human activities on the land surface. Radon enters from radioactive decay in the rock. Iron and manganese dissolve naturally from sediment as water moves underground. Arsenic, chloride, and nitrate seep into groundwater from saltwater intrusion near the Gulf Coast, agricultural fertilizer, and septic systems. Industrial chemicals like PFOS have also contaminated some wells.
Groundwater in this county is hard, with elevated calcium and magnesium, and contains moderate amounts of iron and notably high sodium. The coastal plain geology naturally releases these minerals as water passes through sediment layers. These mineral and contamination characteristics are widespread across wells throughout Harris County, making testing essential for every private well owner in the area.
Harris County wells commonly contain arsenic, uranium, radon, nitrate, and per- and polyfluoroalkyl substances at levels that exceed EPA health standards. Arsenic and uranium can damage organs and increase cancer risk over time. Radon is a radioactive gas that enters through groundwater and can increase lung cancer risk. Nitrate and PFOS are chemicals that build up in your body and can harm your health with long-term exposure.
Hard water in this county's wells causes scale buildup on pipes and fixtures and makes soap less effective. You may notice reddish or brown staining from iron, or a metallic taste. Hard water can shorten the lifespan of water heaters and dishwashers. Elevated sodium can also affect the taste of your water.
Because multiple contaminants exceed EPA standards in Harris County wells, we recommend a comprehensive metals and minerals panel to understand what is actually in your well. Every well is different, and your water may have higher or lower levels than what is common in the county. A comprehensive panel typically costs between two hundred and four hundred dollars. Treatment options like reverse osmosis systems or whole-house filters can address multiple contaminants at once.
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 | 79 | 56% | Moderate | High ⓘ | |
| Iron | 1522 | 13% | High | Moderate | |
| Manganese | 947 | 12% | High | Moderate | |
| PFOS ⓘ municipal | 1319 | 3% | High |
Moderate
Elevated concentration, not % above limit
|
|
| Arsenic | 661 | 3% | High | Low | |
| Nitrate | 216 | 2% | High | Low | |
| Uranium | 371 | 1% | High | Low | |
| Chloride | 1848 | 1% | High | Low | |
| Fluoride | 1567 | 1% | High | Low | |
| Sulfate | 628 | 0% | High | Low | |
| PFHxS ⓘ municipal | 1319 | 0% | High | Low | |
| HFPO-DA (GenX) ⓘ municipal | 1319 | 0% | High | Safe | |
| Lead | 458 | 0% | High | Low | |
| Nitrite | 139 | 0% | High | Low | |
| PFNA ⓘ municipal | 1319 | 0% | High | Safe | |
| PFOA ⓘ municipal | 1319 | 0% | High | Low | |
| Hardness | 390 | — | High | Low | |
| PFBS ⓘ municipal | 1319 | — | High | Low | |
| pH | 1851 | — | High | Low | |
| Sodium | 387 | — | High | 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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