Well water in Texas

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Testing recommended

tested well samples in Texas exceeded the EPA limit for gross alpha (15 pCi/L), based on public data from Texas Water Development Board Groundwater Database and USGS Water Quality Portal.

182,228 test results across 17 contaminants from at least 19,854 wells, 1907 to 2026; chloride has the most at 36,951. Data refreshed September 15, 2026.

Compiled by Nick at Well Water Nerd from public records. How these pages are built

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, 10% of 89 PFOS results in Texas were above the EPA limit of 4 ng/L. In that targeted sampling, 8% of 89 PFOA results in Texas were above the EPA limit of 4 ng/L.

An estimated 1,315,073 people in Texas get their drinking water from a private well, per USGS 2015 county water use.

Separately, the USGS national arsenic model estimates that 7% of the 1,315,073 people on private wells in Texas draw water above 10 ug/L (the model's range is 6% to 9%), from geology and well depth rather than local tests.

What individual samples found

Each row summarizes every public sample for that contaminant inside Texas. 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	Above limit	Samples	Detected	Median	Highest	Limit
Gross alpha 1972 to 2026	12%	2,417	67%	4.27	525	15 pCi/L EPA limit
PFOS 2019 to 2025	10%	89	22%	0	170	4 ng/L EPA limit
Nitrate 1913 to 2026	9%	19,663	85%	1.32	4,520	10 mg/L EPA limit
PFOA 2019 to 2025	8%	89	16%	0	670	4 ng/L EPA limit
Arsenic 1949 to 2026	7%	10,282	48%	0	569	10 ug/L EPA limit
E. coli 2002 to 2021	5%	415	5%	0	140	0 MPN/100mL EPA limit
Fluoride 1913 to 2026	3%	27,446	97%	0.58	168	4 mg/L EPA limit
Radium (226 + 228) 1977 to 2026	2%	3,605	59%	0.23	147	5 pCi/L EPA limit
Uranium 1980 to 2026	2%	4,588	71%	0.903	336	30 ug/L EPA limit
Lead 1968 to 2026	<1%	9,634	24%	0	115	15 ug/L EPA limit
Copper 1968 to 2026	0%	9,386	60%	0.001	1.07	1.3 mg/L EPA limit
Total coliform 2012 to 2017	0%	13	0%	0	0	0 MPN/100mL EPA limit
Chloride 1907 to 2026	no limit	36,951	100%	63	160,000	250 mg/L nuisance level
Sodium 1907 to 2026	no limit	32,254	100%	69	97,000	20 mg/L health guideline
Iron 1911 to 2026	no limit	13,693	59%	10	666,000	300 ug/L nuisance level
Manganese 1939 to 2026	no limit	11,048	53%	0.15	128,000	300 ug/L health guideline
Radon 1990 to 2017	no limit	655	95%	300	8,670	2,000 pCi/L health guideline

Over time

Share of samples above the limit by period. A cell needs ten samples to show; a comparison needs twenty in each period. Later periods sample fewer wells, and often the ones already known to have a problem.

Contaminant	before 2000	2000s	2010s	2020s
Fluoride	3%21,497 samples	5%3,204 samples	3%2,119 samples	5%626 samples
Nitrate	9%11,898 samples	9%4,130 samples	9%2,734 samples	7%901 samples
Arsenic	6%4,118 samples	9%3,406 samples	6%2,184 samples	3%574 samples
Lead	<1%3,812 samples	<1%3,349 samples	0%1,907 samples	0%566 samples
Copper	0%3,763 samples	0%3,245 samples	0%1,814 samples	0%564 samples
Uranium	1%449 samples	2%1,439 samples	2%2,126 samples	2%574 samples

Fluoride, nitrate, arsenic, lead, copper, uranium have held within a few points between the two most recent periods with enough samples.

What this means

The contaminants most often above their limit here are gross alpha (12% of 2,417 samples), pfos (10% of 89 samples), and nitrate (9% of 19,663 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, Iron, and Manganese are widespread in local groundwater. They are mainly a staining and taste problem, but high manganese also carries a health advisory for infants.

What to test for in Texas

1
Gross alpha
12% of 2,417 local samples were above the limit.
2
PFOS
10% of 89 local samples were above the limit.
3
Nitrate
9% of 19,663 local samples were above the limit.
4
PFOA
8% of 89 local samples were above the limit.
5
Arsenic
7% of 10,282 local samples were above the limit.
6
E. coli
5% of 415 local samples were above the limit.
7
Fluoride
3% of 27,446 local samples were above the limit.
8
Volatile organic compounds (VOCs)
28,717 leaking underground storage tank sites on record locally.
9
Metals panel
167 hazardous waste sites on record locally.

Test your Texas well for gross alpha, PFOS and nitrate

Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.

Order the Tap Score well water test kit, from $209 Already tested? Upload the report

Just want bacteria checked first? Tap Score coliform and E. coli test, $99. Coliform and E. coli are the tests every well needs every year.

Want a quick look before paying for a lab? Home well water test strips on Amazon check hardness, iron, pH and nitrate in minutes. They are a screen, not a result: arsenic, bacteria, uranium and PFAS need a certified lab.

Affiliate links: the merchant pays us a commission and the price is the same for you. It does not change what the data above says. As an Amazon Associate we earn from qualifying purchases.

Where to get a well tested in Texas: certified labs, state programs and prices.

Already have results back? Get your lab report read against the Texas numbers, $29. Every line explained, ranked by what matters, with the fix for each.

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Send me the Texas report

The numbers above, which tests to order and where, and the treatment that fits the local profile, in one email.

The rock under Texas

Edwards-Trinity aquifer system

Sandstone and carbonate-rock. Layered sandstone and limestone means a well may draw from either. Hardness and iron are routine, and the limestone layers can carry bacteria and nitrate from the surface quickly, so test for both yearly.

Classification from the USGS Principal Aquifers of the United States (national map, 2003 edition, GIS release 2015), read at the state centroid. A single well can sit in a different unit, especially near a boundary.

Official help in Texas

Two places to start that are not selling anything: the state program that answers private well questions, and its list of labs certified to run drinking water tests. A certified lab is the difference between a result you can act on and a number.

Private Wells, Texas Groundwater Protection Committee
Environmental Laboratory (NELAP) Accreditation, TCEQ

Contamination sources on record in Texas

TCEQ records 28,717 leaking underground storage tank sites and 167 hazardous waste sites in Texas, among 31,488 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.

28,717: leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
167: hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
2,604: lined landfills and transfer facilities

Treatment that fits the local profile

Gross alpha

Point-of-use reverse osmosis; Water softener (cation exchange) for radium; Anion exchange for uranium

PFOS

Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange

Nitrate

Point-of-use reverse osmosis; Anion exchange; Distillation

PFOA

Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange

Arsenic

Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange

Systems we would look at first

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For gross alpha

Under-sink reverse osmosis system

under-sink or countertop, about $300

Look for NSF/ANSI 58 certification listing the contaminant you need removed.

For PFOS

Aquasana SmartFlow reverse osmosis

under-sink or countertop, about $225

Certified to NSF/ANSI 58 and 53 to reduce arsenic (96%, pentavalent), fluoride (90%), lead (99%), nitrate, nitrite and PFOA/PFOS at the kitchen tap, with a remineralizer.

For PFOS

Whole-house PFAS carbon system

whole-house, at the point of entry, about $3,000

Granular activated carbon certified to NSF/ANSI 53 for PFOA and PFOS; replace media on schedule.

For PFOS

Aquasana HealthShield whole-house filter

whole-house, at the point of entry, about $2,099

Whole-house carbon system the maker certifies to reduce PFAS (PFOA and PFOS) and VOCs at every tap; a UV option adds bacteria protection.

For PFOA

Aquasana Claryum 3-Stage under-sink filter

under-sink or countertop, about $175

Certified to NSF/ANSI 53 to reduce 99% of lead and 99.7% of PFOA and PFOS at the tap. Not a fix for arsenic, nitrate or bacteria.

For arsenic

Whole-house arsenic and uranium filter

whole-house, at the point of entry, about $2,500

Adsorptive iron-based media; sized to your well yield.

Common questions

Is there arsenic in well water in Texas?

Arsenic was detected in 48% of 10,282 public well samples in Texas, and 7% 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 Texas?

The median radon level across 655 public samples in Texas was 300 pCi/L, with a high of 8,670 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.

How often should I test a private well in Texas?

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.

Counties in Texas

Want the numbers themselves? Download the Texas dataset as CSV, every county and town, with the sources named.

Sources

Texas Water Development Board Groundwater Database: 114,431 samples in Texas. Water quality samples from the Texas Water Development Board Groundwater Database, collected by TWDB, groundwater conservation districts and cooperators. Retrieved September 9, 2026.
USGS Water Quality Portal: 67,797 samples in Texas. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
USGS national arsenic model (Ayotte 2017): estimated share of 1,315,073 people on private wells in Texas above 10 ug/L of arsenic, from geology, well depth and land use. County estimates of domestic well users with arsenic above 10 ug/L from the USGS national logistic regression model (Ayotte, Medalie and Qi, 2017), with private well population from the USGS 2015 county water-use compilation (Dieter and others, 2018). Retrieved September 15, 2026.
TCEQ regulated sites: 31,488 regulated sites located in Texas. 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.