Guide · Updated September 26, 2026

Arsenic in Texas Well Water

A clear glass of Texas well water is not a test. You cannot taste, see, or smell arsenic, and neighboring wells can still differ. The only number that counts is a certified-lab micrograms-per-liter (µg/L) result. A county map, a neighbor’s well, or a catalog is not a diagnosis.

This page is a reading order for that sheet — not a medical consult and not a shopping list. This site does not turn a µg/L into a risk score. If the number is high or the units are unclear, take the sheet to your county health department or a licensed Texas water professional.

Private wells are unregulated. The Safe Drinking Water Act does not cover private wells; testing and treatment are the owner’s job. EPA’s private-wells pages, the Texas Water Development Board’s private-well sampling page, and CDC’s well-testing guidance put the schedule on the owner. Nobody mails you a Consumer Confidence Report.

If you are on a city or water-supply-corporation system, look up that system’s reports through TCEQ’s drinking-water quality tool. That Consumer Confidence Report is not a private-well sheet.

What 10 µg/L means — and what it is not

EPA’s National Primary Drinking Water Regulations and the Arsenic Rule set a public-water-system MCL of 10 µg/L (10 ppb / 0.010 mg/L). That is a Safe Drinking Water Act limit for community systems. Private wells are not under that Act. Do not call 10 µg/L a kitchen-tap legal limit.

Use 10 µg/L as a teaching comparison on a private-well sheet. EPA’s public-system MCL goal is 0 µg/L — a non-enforceable goal, not a private-well statute.

Units. µg/L and ppb match. 0.010 mg/L = 10 µg/L. Convert mg/L before you compare. If the reporting limit sits at or above 10 µg/L, ask for a lower one. How to read a well water lab report is the decoder.

Why Texas wells pick up arsenic

Arsenic in Texas groundwater is usually geologic — released from aquifer minerals into the water — not a kitchen-sink spill. Bureau of Economic Geology work for TCEQ, and the 2024 updated statewide assessment, point to elevated arsenic zones especially in parts of the southern High Plains and portions of the Gulf Coast, with public-system arsenic issues historically clustered in those same broad regions.

USGS models and maps estimate the probability that private-well arsenic exceeds thresholds such as 10 µg/L across the conterminous United States. Those products are area risk models, not a reading for your wellhead. USGS Circular 1332 is the national domestic-well backdrop: arsenic showed up above human-health benchmarks in that study. A national paper is not your well.

A county average, a public-system violation map, or a modeled “elevated risk” flag is published geography — not your well. Only a sample from your tap describes your water. This page will not invent a Texas occurrence percent.

The Minnesota arsenic, Maine arsenic, and Wisconsin arsenic pages are the peer-state versions of the same split: a map is not a kitchen tap.

How often to test

CDC’s annual backbone for private wells is still coliform bacteria and nitrate every year, then add-ons when geology or a state program says so. In much of Texas, arsenic is that add-on.

The Texas Well Owner Network (TWON) — Texas A&M AgriLife Extension / Texas Water Resources Institute — tells owners to test at least annually for bacteria, nitrates, and contaminants of local concern such as arsenic. TWON Water Well Basics also notes that arsenic and radionuclides can occur naturally. Screening events sometimes include arsenic when the well is a drinking source; a screen is a first pass, not a substitute for a TCEQ-accredited drinking-water method when you need a legal-grade µg/L. TWRI’s well-testing write-up makes the same case: a screen is education, not the sheet you treat from.

Texas Groundwater Protection Committee owner FAQs point the same way: annual E. coli and nitrate-nitrogen, plus use TCEQ’s NELAP accredited-lab list when you need a certified method.

If you treat, sample the tap you cook and drink from (after treatment) unless the lab asks for a raw-side bottle for design. Bacteria or nitrate on the same sheet goes to the health department first. Do not shop an arsenic stage while those lines are open.

Get a certified-lab µg/L — not a store-kit guess

Start at this site’s Texas certified-lab inventory. Accreditation is by matrix, method, and analyte. A coliform certificate is not an arsenic (metals) certificate.

Open TCEQ’s Environmental Laboratory (NELAP) Accreditation page and use the public list of accredited laboratories. Confirm drinking-water arsenic (or a total-metals method covering arsenic) on the current certificate, then call about bottles, hold times, and whether the lab accepts a private-well / residential sample. TCEQ also publishes steps to locate an accredited laboratory. Laboratory Accreditation: 512-239-3754, labprgms@tceq.texas.gov.

TWDB notes that private-well testing is the owner’s job and that published costs range from a cheap bacteria screen up to a full drinking-water-standards panel. Those are TWDB’s published ranges, not a price this site invents. Hours change. Call before you drive.

Sample the cooking and drinking tap. Untreated: usually kitchen cold. Treated: after the tank, unless the lab says otherwise. Use the lab’s bottle. Run the cold tap a few minutes first. Ship within the lab’s holding time.

A store strip kit is a screen. Well water test kits explains that split. Nationwide index: certified labs by state. Lab news: /labs/texas/news. Sibling pages: Nitrates in Texas Well Water; Arsenic in Minnesota Well Water; Arsenic in Maine Well Water; Arsenic in Wisconsin Well Water.

Mail-in certified-lab kits

Tap Score / SimpleLab is an approved class example of a mail-in certified-lab kit — not a ranked pick. Pair it with a lab from /labs/texas. Bacteria or nitrate still goes to the health department. See the disclosure.

After the sheet: classes, not a catalog

Name the class after you have a µg/L. Then look the model up in the NSF drinking-water treatment-unit database. NSF is a claim on a listed model — often NSF/ANSI 58 for reverse osmosis — not a badge this site awards. This page does not rank brands.

Treatment classes people ask about for arsenic:

• Point-of-use reverse osmosis (drinking and cooking). Look for NSF/ANSI 58 listings that name arsenic.
• Adsorptive media — a charged bed (often iron-oxide or titanium-dioxide class claims on NSF DWTU lists). Read pH range and replacement interval.
• Anion exchange, where the sheet and a licensed installer say it fits. Salt regenerates the resin. That is not a hardness softener.

A conventional softener or an activated-carbon filter alone will not remove arsenic. Boiling concentrates it. Treatment order after the pressure tank: sediment first, then the arsenic class, then a softener last if hardness remains.

A whole-house iron or sulfur filter is the wrong class for arsenic. Those catalogs stay off this page. Do not buy a pitcher “for arsenic.”

If bacteria is present, stop. Health department first. An arsenic cartridge on a contaminated well is the wrong Monday.

For well construction and pump work, use a licensed Texas water well driller or pump installer (TDLR license search). Retest the treated tap.

What to do this week

1. Open /labs/texas. Confirm arsenic (metals) on the current TCEQ NELAP drinking-water certificate for a lab that accepts private homeowners.
2. Sample the cooking/drinking tap. If you treat, sample after treatment unless the lab says otherwise. Ask about bottle type and hold time.
3. Put the µg/L next to 10. Convert mg/L first. Above that public-system MCL line, plan a treatment class or an alternate drinking source and talk with your county health department if you cannot read the sheet.
4. If bacteria or nitrate is also flagged, call the health department before you shop an arsenic stage.
5. Only after the sheet: decide point-of-use RO versus adsorptive media versus anion exchange, then NSF lookup. Not a softener. Not a pitcher “for arsenic.”
6. Optional: check whether your county AgriLife office or TWON has a screening event — then confirm anything high at a TCEQ-accredited lab.

Bottom line

Arsenic is invisible in Texas well water and often geologic. Parts of the southern High Plains and Gulf Coast show elevated groundwater arsenic in published assessments — that is geography, not your wellhead. Order a certified-lab arsenic test from the Texas inventory. Compare µg/L to EPA’s public-system MCL of 10 — as a teaching number, not a private-well legal limit. Treatment class comes after the sheet. Bacteria and nitrate still go to the health department.

Updated 2026-09-26.