Well water in Montgomery County, Texas
In Montgomery County, 7% of 43 tested well samples exceeded the EPA limit for radium (226 + 228) (5 pCi/L), based on public data from USGS Water Quality Portal and Texas Water Development Board Groundwater Database.
48 individual samples from 41 wells, 1931 to 2025. Data refreshed September 9, 2026.
TWDB samples an ambient monitoring network of wells on a rotation, so these describe aquifers, not a survey of homeowners' tests. In that targeted sampling, 0% of 11 PFOA results in Montgomery County were above the EPA limit of 4 ng/L. In that targeted sampling, 0% of 11 PFOS results in Montgomery County were above the EPA limit of 4 ng/L.
What individual samples found
Each row summarizes every public sample for that contaminant inside Montgomery County. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.
| Contaminant | Samples | Detected | Above limit | Median | Highest | Limit | |
|---|---|---|---|---|---|---|---|
| Radium (226 + 228) 2007 to 2015 | 43 | 91% | 7% | 0.46 | 147 | 5 pCi/L EPA limit | |
| Uranium 2003 to 2025 | 48 | 69% | 0% | 0.039 | 1.47 | 30 ug/L EPA limit | |
| Fluoride 1942 to 2025 | 31 | 100% | 0% | 0.2 | 0.7 | 4 mg/L EPA limit | |
| PFOA 2024 to 2025 | 11 | 9% | 0% | 0 | 1.3 | 4 ng/L EPA limit | |
| PFOS 2024 to 2025 | 11 | 0% | 0% | 0 | 0 | 4 ng/L EPA limit | |
| Chloride 1931 to 2025 | 43 | 100% | no limit | 36 | 2,140 | 250 mg/L nuisance level | |
| Sodium 1942 to 2025 | 33 | 100% | no limit | 30 | 522 | 20 mg/L health guideline | |
| Radon 2007 to 2014 | 16 | 100% | no limit | 550 | 1,240 | 2,000 pCi/L health guideline |
Sampled fewer than 10 times, too few to summarize: E. coli (5), Arsenic (2), Nitrate (1), Copper (1), Lead (1), Manganese (2), Iron (2).
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What this means
The contaminants most often above their limit here are radium (226 + 228) (7% of 43 samples). A well next door can differ sharply from yours because bedrock fractures, well depth and plumbing all matter, so these rates describe the area, not your tap.
Chloride is widespread in local groundwater. It is mainly a staining and taste problem, but high manganese also carries a health advisory for infants.
What to test for in Montgomery County
- Volatile organic compounds (VOCs)271 leaking underground storage tank sites on record locally.
- Metals panel2 hazardous waste sites on record locally.
- Radium (226 + 228)7% of 43 local samples were above the limit.
- Coliform bacteriaRecommended for every private well, every year.
- RadonMedian local reading is 550 pCi/L.
- FluorideDetected in 100% of local samples.
- CopperDetected in 100% of local samples.
- ChlorideDetected in 100% of local samples.
- NitrateRecommended for every private well, especially near farms or septic systems.
Contamination sources on record in Montgomery County
TCEQ records 271 leaking underground storage tank sites and 2 hazardous waste sites in Montgomery County, among 310 regulated sites in total. Groundwater does not follow property lines, so a well within a few hundred feet of one of these is worth testing for what that site could release.
- 271
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 2
- hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
- 37
- lined landfills and transfer facilities
Treatment that fits the local profile
- Radium (226 + 228)
- Water softener (cation exchange); Point-of-use reverse osmosis
- Fluoride
- Point-of-use reverse osmosis; Activated alumina; Distillation
- Copper
- Neutralizing filter to raise pH; Point-of-use reverse osmosis
- Chloride
- Point-of-use reverse osmosis; Distillation
Get your Montgomery County water tested at home
A licensed local water treatment company tests your tap water in your home, walks you through the numbers, and quotes treatment only if something needs fixing. Free, about 30 minutes, no obligation. Tell us what you need and we match you with a company that serves Montgomery County.
Common questions
Is there arsenic in well water in Montgomery County?
Arsenic was detected in 100% of 2 public well samples in Montgomery County, and 0% were above the EPA limit of 10 ug/L. Arsenic has no taste or smell; a lab test is the only way to know your level.
How high is radon in well water in Montgomery County?
The median radon level across 16 public samples in Montgomery County was 550 pCi/L, with a high of 1,240 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in Montgomery County?
Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.
Sources
- USGS Water Quality Portal: 139 samples in Montgomery County. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
- Texas Water Development Board Groundwater Database: 111 samples in Montgomery County. Water quality samples from the Texas Water Development Board Groundwater Database, collected by TWDB, groundwater conservation districts and cooperators. Retrieved September 9, 2026.
- TCEQ regulated sites: 310 regulated sites located in Montgomery County. Leaking petroleum storage tank sites, state Superfund sites and municipal solid waste landfills from the Texas Commission on Environmental Quality. Retrieved September 9, 2026.
Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.