Well water in Webb County, Texas

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Testing recommended

tested well samples in Webb County exceeded the EPA limit for arsenic (10 ug/L), based on public data from Texas Water Development Board Groundwater Database and USGS Water Quality Portal.

822 test results across 14 contaminants from at least 57 wells, 1961 to 2014; nitrate has the most at 111. 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.

An estimated 498 people in Webb County get their drinking water from a private well, per USGS 2015 county water use. That is about <1% of residents.

Separately, the USGS national arsenic model estimates that 3% of the 498 people on private wells in Webb County draw water above 10 ug/L (the model's range is 2% to 4%), from geology and well depth rather than local tests.

What individual samples found

Each row summarizes every public sample for that contaminant inside Webb 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	Above limit	Samples	Detected	Median	Highest	Limit
Arsenic 1990 to 2014	10%	81	15%	0	99	10 ug/L EPA limit
Uranium 1990 to 2014	8%	52	15%	0	61	30 ug/L EPA limit
Nitrate 1990 to 2014	<1%	111	29%	0	26.1	10 mg/L EPA limit
Fluoride 1965 to 2014	0%	97	99%	0.88	3.08	4 mg/L EPA limit
Lead 1990 to 2014	0%	75	4%	0	9.5	15 ug/L EPA limit
Copper 1990 to 2014	0%	35	51%	0.001	0.011	1.3 mg/L EPA limit
Radium (226 + 228) 1990 to 2013	0%	16	88%	0.1	3.2	5 pCi/L EPA limit
Chloride 1961 to 2014	no limit	97	98%	202	1,810	250 mg/L nuisance level
Sodium 1965 to 2014	no limit	95	98%	405	1,700	20 mg/L health guideline
Iron 1972 to 2014	no limit	76	61%	41.4	963	300 ug/L nuisance level
Manganese 1990 to 2014	no limit	75	81%	5.52	102	300 ug/L health guideline

Sampled fewer than 10 times, too few to summarize: Gross alpha (5), E. coli (1), Radon (6).

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
Nitrate	1%93 samples	0%11 samples	n/a	n/a
Fluoride	0%80 samples	0%11 samples	n/a	n/a
Arsenic	11%64 samples	0%11 samples	n/a	n/a
Lead	0%58 samples	0%11 samples	n/a	n/a
Copper	0%19 samples	0%11 samples	n/a	n/a

Closer than the county

See the sampled wells near your address

The same records, drawn around one point: which wells within a few miles were sampled and what they found, how deep the wells next to you were drilled, and any leaking tank or cleanup site within a mile.

Check my address

What this means

The contaminants most often above their limit here are arsenic (10% of 81 samples), uranium (8% of 52 samples), and nitrate (<1% of 111 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 Webb County

1
Arsenic
10% of 81 local samples were above the limit.
2
Uranium
8% of 52 local samples were above the limit.
3
Nitrate
<1% of 111 local samples were above the limit.
4
Coliform bacteria
Recommended for every private well, every year.
5
Radon
Median local reading is 950 pCi/L.
6
Fluoride
Detected in 99% of local samples.
7
Chloride
Detected in 98% of local samples.
8
Volatile organic compounds (VOCs)
197 leaking underground storage tank sites on record locally.

Test your Webb County well for arsenic, uranium 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 Webb County numbers, $29. Every line explained, ranked by what matters, with the fix for each.

The rock under Webb County

Texas coastal uplands aquifer system

Semiconsolidated sand. Coastal plain sands like these give steady yields at moderate depth. Salt water and sodium are the usual issues near the coast, and nitrate where the water table is shallow; arsenic and radon from bedrock are less common.

Classification from the USGS Principal Aquifers of the United States (national map, 2003 edition, GIS release 2015), read at the county 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 Webb County

TCEQ records 197 leaking underground storage tank sites in Webb County, among 207 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.

197: leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
10: lined landfills and transfer facilities

Treatment that fits the local profile

Arsenic

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

Uranium

Point-of-use reverse osmosis; Anion exchange; Whole-house anion exchange

Nitrate

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

Chloride

Point-of-use reverse osmosis; Distillation

Systems we would look at first

Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.

For arsenic

Under-sink reverse osmosis system

under-sink or countertop, about $300

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

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.

For arsenic

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.

Free, no obligation

Get on the list for a free in-home water test in Webb County

No water treatment company serves Webb County through Well Water Nerd yet. We are signing licensed companies on county by county: they test at your tap for free, walk you through the numbers, and quote treatment only if something needs fixing. Leave your details and you are first in line. Nothing is shared until a company joins for Webb County, and you get an email naming it first.

Common questions

Is there arsenic in well water in Webb County?

Arsenic was detected in 15% of 81 public well samples in Webb County, and 10% 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 often should I test a private well in Webb 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.

Counties near Webb County

Closest first. Groundwater does not stop at a line on a map, so the next county over is a fair second opinion.

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: 422 samples in Webb County. 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: 400 samples in Webb 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.
USGS national arsenic model (Ayotte 2017): estimated share of 498 people on private wells in Webb County 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: 207 regulated sites located in Webb 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.