Guide · Updated September 25, 2026

Nitrates in Texas Well Water

Nitrate does not rust a sink. It does not color the glass. You cannot taste, smell, or see it. The only number that counts is a certified-lab result in mg/L as nitrogen (nitrate-N). Until that sheet is in your hand, a county average, a neighbor’s well, or a treatment catalog is not a diagnosis.

Texas private wells are not regulated like a city system. The Safe Drinking Water Act does not cover private wells; testing and treatment are the owner’s job. TCEQ’s “How is my Drinking Water Quality?” page puts regular testing on the owner and points at an accredited drinking-water laboratory. The Texas Water Development Board says the same: the State of Texas does not regulate the water quality of private water wells.

This page is a reading order for that sheet. It is not a medical consult and not a shopping list. EPA and Texas A&M AgriLife publish infant-related language on their nitrate pages. This site does not reprint that list as a diagnosis and will not turn a mg/L into a personal risk score. If the number is high or the units are unclear, take the sheet to the local health department.

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 mg/L as N means — and what it is not

EPA’s National Primary Drinking Water Regulations table lists nitrate measured as nitrogen with an MCL of 10 mg/L. That is the same magnitude as 10 ppm. Nitrite as nitrogen is a different line (1 mg/L). A nitrate number is not a nitrite number. EPA lists the public-system health concern as methemoglobinemia (“blue baby syndrome”) in infants under six months. This page does not turn that sentence into a household diagnosis.

That MCL is a Safe Drinking Water Act limit for public systems. Private wells are not under that Act. Do not call 10 mg/L as N a kitchen-tap legal limit. It is the comparison number people already know, and the line AgriLife and EPA use when they talk about nitrate in drinking water.

Units. Ask the lab whether the sheet is as N or as NO₃. Those are not interchangeable. Ten milligrams per liter as nitrogen is the MCL. Ten milligrams per liter as nitrate ion is a different quantity — about 44 mg/L as NO₃. If your sheet says 30 mg/L and does not say which, ask the lab before you panic or relax. If the reporting limit sits at or above 10 mg/L as N, you bought a test that cannot tell you whether you are under the line. How to read a well water lab report is the decoder.

Texas A&M AgriLife’s Drinking Water Problems: Nitrates explains that high nitrate is harmful to very young infants and susceptible adults, and covers exposure, health effects, and removal. Pregnant households and anyone mixing infant formula should talk to a doctor about any result near the limit — not this directory.

Why Texas wells pick up nitrate

Nitrate in groundwater usually traces back to:

• Fertilizer and manure on cropland, pasture, and around feedlots and dairies.
• Septic systems too close to the well or failing.
• Poor well construction — a missing sanitary seal, a cracked casing, a wellhead in a low spot where runoff ponds.
• Shallow wells in permeable aquifers, where surface water reaches the water table quickly.

The Texas Water Development Board samples groundwater quality statewide and publishes county-level results, but those samples cover aquifers, not your wellhead. A neighbor’s clean result or a county average does not describe your well. Only a sample from your tap does. This page will not invent a Texas occurrence percent.

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

How often to test

CDC recommends testing a private well every year for total coliform bacteria, nitrates, total dissolved solids, and pH, and sooner if there is a new baby in the house, a flood, a nearby septic or fertilizer change, or a change in taste or appearance.

The Texas Well Owner Network (TWON), run by Texas A&M AgriLife, holds county screening events where well owners bring samples for nitrate, bacteria, and salinity screening, plus training on wellhead protection. Screening is a good first pass. Confirm anything high at a TCEQ-accredited lab before you treat or change the well.

Bacteria on the same sheet still goes to the health department first. Do not shop a nitrate stage while coliform is open.

Get a certified-lab mg/L as N — not a clinic guess alone

Start at this site’s Texas certified-lab inventory. Accreditation is by matrix, method, and analyte. A wastewater certificate is not a drinking-water nitrate certificate. Open TCEQ’s Environmental Laboratory (NELAP) Accreditation page and the steps to locate an accredited laboratory. Set matrix to drinking water. Confirm nitrate is on the current certificate. Then call: ask whether they accept a private-well / residential sample, which bottle they issue, and the hold time. Nationwide index: certified labs by state. Lab news: /labs/texas/news. Sibling page: Arsenic in Texas Well Water.

TWDB notes costs range from about $20 for a coliform / E. coli presence-absence test up to about $400 for a full drinking-water-standards analysis. 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. If you also need a bacteria sample, TCEQ’s GI-433, How to Sample Your Private Well Water for Microbial Contaminants, walks through collection.

A store strip is a screen. Well water test kits explains that split. Tap Score / SimpleLab is an approved class example of a mail-in certified-lab kit — not a ranked pick (Awin tracked URL; see the disclosure). Pair any kit with a lab from /labs/texas. Confirm nitrate and coliform on the order form.

What to do with the number

Do not boil high-nitrate water. Boiling does not remove nitrate; it concentrates it as water evaporates. Use treatment or an alternative source instead.

Before buying equipment, look for the cause: wellhead grade and cap, distance to septic, fertilizer or manure storage near the well. A licensed Texas water well driller or pump installer can inspect construction. This site will not turn 10 mg/L as N into a personal risk score.

After the sheet: classes, not a catalog

Name the class after you have a mg/L as N. 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.

Nitrate is removed by a short list of technologies, and a softener or iron filter is not one of them:

• Point-of-use reverse osmosis at the kitchen sink, certified for nitrate reduction under NSF/ANSI 58. The usual first step for drinking and formula water.
• Nitrate-selective anion exchange for whole-house treatment when levels are high throughout and a licensed installer says it fits.
• Distillation at point of use.

A water softener alone does not remove nitrate. Do not buy salt “for nitrate.” An oxidizing iron filter is the wrong class.

Check any unit against NSF for a nitrate claim and retest after install. RO membranes also need clear pretreated water; see treatment order after the pressure tank. Even after a unit is in, test the treated water at least yearly. If the unit fails, infants should not drink that tap as a precaution — that is the same caution sister nitrate pages already use.

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

Bottom line

A Texas private well with an unknown nitrate level is a question, not a crisis. Order a certified-lab nitrate test from the Texas inventory. Compare mg/L as N to EPA’s public-system MCL of 10 — as a teaching number, not a private-well legal limit. At or above 10, call the health department, keep infants off the tap, and do not boil. Treatment class comes after the sheet. A softener is the wrong class. Bacteria still goes to the health department.

Updated 2026-09-25.