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Texas water profile

Nitrate in Texas community water systems

Texas is not one nitrate story but several, because it sits on several different aquifers. The higher public-system results concentrate on the Southern High Plains, with a second, karst setting in central Texas. See where the pattern gathers and what each reporting system measured in the three years from August 9, 2023 to August 9, 2026.

Browse all 4,473 Texas systems →

Search by the utility or system name shown on a water bill. Example: San Antonio Water System. Private wells are not in this inventory.

94%
of the state’s 4,740 active community water systems have a current result here
4,473
systems with a current nitrate result
32,102,337
people served by those reporting systems
2.6%
of reporting systems at or above 5 mg/L
How to read these numbers Each system is placed into a band by its most recent reported result within a rolling three-year window. The bands describe how strongly human activity, read from nitrate, has marked a water source; they are not a safety verdict. Figures describe system reporting, not nitrate measured at an individual tap.

How Texas's systems fall across the five bands

Most systems report below 3 mg/L

Natural background
0.00–0.99 mg/L as N
3,841 systems · 28,475,465 served
Human impact likely
1.00–2.99 mg/L as N
414 systems · 3,331,340 served
Human impact clear
3.00–4.99 mg/L as N
101 systems · 192,672 served
Health-study range
5.00–9.99 mg/L as N
86 systems · 84,675 served
Above the federal limit
10.00 mg/L and above
31 systems · 18,185 served

Each system appears in one band only, placed by its most recent reported result in the current three-year window. Counts sit beside people served so a small number of larger systems cannot hide behind a row of tiny ones. Of the 117 systems reporting 5 mg/L or more, 78 stayed at or above 5 across the whole three-year range; the other 39 reached it only on a high sample and otherwise ran lower.

Most recent reading Jun 2026; the typical system was last tested around Jan 2026. 4,410 systems sampled their own water; 63 systems carry a supplier’s result.

The named systems

Every reading here belongs to a utility with a name

Highest recent readings
SystemMost recent resultBandBased onPeople served
Whitharral Wsc28.30 mg/LApr 2026Above the federal limit9 samples200
Eola Wsc26.10 mg/LOct 2025Above the federal limit5 samples165
City Of Burkburnett26.00 mg/LMay 2026a high point — runs lowerAbove the federal limit18 samples10,978
South Midland County Water System20.30 mg/LMar 2025Above the federal limit4 samples165
Canyon Dam Mobile Home Park18.00 mg/LFeb 2026Above the federal limit7 samples108
Margies Mhp17.50 mg/LMay 2026Above the federal limit9 samples60
Greenwood Terrace M H Subdivision17.00 mg/LMay 2026Above the federal limit7 samples120
Franklin Water Systems 317.00 mg/LMay 2026a high point — runs lowerAbove the federal limit31 samples201
Largest systems
SystemMost recent resultBandBased onPeople served
City Of Houston0.12 mg/LJun 2026Natural background49 samples2,970,543
San Antonio Water System0.66 mg/LApr 2026Natural background122 samples2,113,151
Dallas Water Utility0.80 mg/LJul 2025Natural background3 samples1,356,479
City Of Austin Water & Wastewater0.12 mg/LMay 2026Natural background6 samples1,115,323
City Of Fort Worth0.40 mg/LApr 2026Natural background25 samples955,900

Each result shows its date and what it rests on, so a lone sample is never taken for a settled measurement. A single high sample is not a complete account of what a household drinks.

Where higher nitrate concentrates

Higher results concentrate on the Southern High Plains

Human impact is clear on drinking water served in 83 of Texas’s 254 counties. Each is shaded by how many of its systems reported 3.00 mg/L as N or above. Shading counts systems, not severity — a county with many small utilities can outrank one holding a single larger system that reads higher. The table beside the map splits the two bands so that difference stays visible.

TX counties shaded by number of community water systems reporting nitrate at or above 3.00 mg/L as NCounties are shaded by how many community water systems reported nitrate at or above 3.00 mg/L as N in the three years from August 9, 2023 to August 9, 2026. The same counts appear in the table below this map.Walker County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveBrooks County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveDeaf Smith County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveHockley County — 1 system at 3.00–4.99 mg/L as N; 5 systems at 5.00 mg/L as N or aboveTom Green County — 2 systems at 3.00–4.99 mg/L as N; 4 systems at 5.00 mg/L as N or aboveCottle County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveTaylor County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveYoakum County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveChildress County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveGillespie County — 2 systems at 3.00–4.99 mg/L as N; 2 systems at 5.00 mg/L as N or aboveHansford County — 2 systems at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveRunnels County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveHale County — 4 systems at 3.00–4.99 mg/L as N; 3 systems at 5.00 mg/L as N or aboveDuval County — 1 system at 3.00–4.99 mg/L as N; 4 systems at 5.00 mg/L as N or aboveMoore County — 2 systems at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveMartin County — 0 systems at 3.00–4.99 mg/L as N; 2 systems at 5.00 mg/L as N or aboveCochran County — 2 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveFisher County — 1 system at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveBaylor County — 0 systems at 3.00–4.99 mg/L as N; 2 systems at 5.00 mg/L as N or aboveLipscomb County — 3 systems at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveDonley County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveBriscoe County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveGray County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveHall County — 2 systems at 3.00–4.99 mg/L as N; 3 systems at 5.00 mg/L as N or aboveBrown County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveGaines County — 1 system at 3.00–4.99 mg/L as N; 2 systems at 5.00 mg/L as N or aboveKing County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveSchleicher County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveLynn County — 1 system at 3.00–4.99 mg/L as N; 3 systems at 5.00 mg/L as N or aboveNolan County — 1 system at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveStonewall County — 0 systems at 3.00–4.99 mg/L as N; 3 systems at 5.00 mg/L as N or aboveHemphill County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveCastro County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveUpton County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveMidland County — 3 systems at 3.00–4.99 mg/L as N; 11 systems at 5.00 mg/L as N or abovePalo Pinto County — 0 systems at 3.00–4.99 mg/L as N; 2 systems at 5.00 mg/L as N or aboveLamb County — 5 systems at 3.00–4.99 mg/L as N; 3 systems at 5.00 mg/L as N or aboveEastland County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveLubbock County — 2 systems at 3.00–4.99 mg/L as N; 13 systems at 5.00 mg/L as N or aboveAndrews County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveKnox County — 0 systems at 3.00–4.99 mg/L as N; 2 systems at 5.00 mg/L as N or aboveLlano County — 4 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveWheeler County — 1 system at 3.00–4.99 mg/L as N; 3 systems at 5.00 mg/L as N or aboveKent County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveComal County — 3 systems at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveSherman County — 2 systems at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveWilliamson County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveClay County — 0 systems at 3.00–4.99 mg/L as N; 2 systems at 5.00 mg/L as N or aboveFoard County — 2 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveConcho County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveBrewster County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveBurnet County — 5 systems at 3.00–4.99 mg/L as N; 3 systems at 5.00 mg/L as N or aboveOchiltree County — 1 system at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveMedina County — 2 systems at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveGlasscock County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveTravis County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveHoward County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveTrinity County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveBailey County — 1 system at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or abovePresidio County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveWilbarger County — 3 systems at 3.00–4.99 mg/L as N; 3 systems at 5.00 mg/L as N or aboveRandall County — 1 system at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveWichita County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveSmith County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveReagan County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveTarrant County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveWebb County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveKleberg County — 3 systems at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveHarris County — 2 systems at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveHardeman County — 6 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveFloyd County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveParmer County — 2 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveEl Paso County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveJim Wells County — 2 systems at 3.00–4.99 mg/L as N; 2 systems at 5.00 mg/L as N or aboveEctor County — 1 system at 3.00–4.99 mg/L as N; 4 systems at 5.00 mg/L as N or aboveParker County — 5 systems at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveDawson County — 0 systems at 3.00–4.99 mg/L as N; 3 systems at 5.00 mg/L as N or aboveHaskell County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveTerry County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveArcher County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveHartley County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveCollingsworth County — 0 systems at 3.00–4.99 mg/L as N; 3 systems at 5.00 mg/L as N or aboveBexar County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or above
none1–23–56–1112–2526+Number of drinking water systems reporting ≥3.00 mg/L NO₃–N per county as of August 9, 2026

Lubbock leads this layer with 13 reporting systems, followed by Midland, Hockley, Duval. Higher results concentrate on the Southern High Plains.

Counties with the most systems at or above 3 mg/L as N
County3–4.99≥5Total ≥3
Lubbock21315
Midland31114
Burnet538
Lamb538
Hale437

Counts use each system's most recent reported result in the current three-year window. A system appears in only one of the two bands.

Find a specific Texas system

What the statewide pattern says

Several aquifers, and nitrate rarely travels alone

Texas's higher nitrate is an irrigated-High-Plains pattern delivered by playa-focused recharge, with a karst pathway in central Texas — and it often shows up with naturally occurring arsenic or fluoride.

The Southern High Plains — the Panhandle's Ogallala — is the agricultural-nitrate core, and it moves by playa-focused recharge. Regional recharge across the plains is almost nothing, but the shallow playa basins and irrigated fields concentrate the downward flow of water and nitrate; Texas Water Development Board recharge studies put playa-focused and irrigated recharge many times higher than the regional background (Nolan and Hitt, 2006).

Central Texas is a different mechanism entirely. The Edwards is carbonate karst — rapid, near-direct pathways from the surface into the aquifer — so agricultural and urban nitrogen can move fast, the same vulnerability as a sinkhole landscape. The supported source reading on the High Plains is agricultural — irrigated cropland; in the Edwards, mixed agricultural and urban nitrogen on fast karst pathways. Neither reading certifies a source at an individual system.

The Texas headline, though, is company. Groundwater here often carries nitrate alongside naturally occurring arsenic and fluoride, and near oil-and-gas activity, other contaminants. A nitrate number alone can undercount what is in the water (Dubrovsky and others, 2010) — which is why the testing advice for Texas wells is a broad panel, not nitrate only.

The general science — how nitrate moves, why some ground is vulnerable, and why the legacy lingers — is laid out with its sources on Where nitrate comes from.

Questions this page answers

What the Texas pattern does—and does not—say

Where does nitrate concentrate in Texas community water systems?

Lubbock leads this layer with 13 reporting systems, followed by Midland, Hockley, Duval. Higher results concentrate on the Southern High Plains.

Why does Texas advice say to test more than nitrate?

Because Texas groundwater frequently carries nitrate alongside naturally occurring arsenic and fluoride, and in oil-and-gas country, additional contaminants. A nitrate-only test can undercount what is in the water; a broad panel is the prudent screen.

Can this page say the source is agriculture?

At the zone level, on the Southern High Plains, yes — irrigated cropland delivered by playa-focused recharge. In the Edwards karst, the reading is mixed agricultural and urban nitrogen on fast pathways. Neither certifies a source at an individual system.

Does a high public-system result mean a nearby private well is high?

No. It is a local sentinel, not a well-specific result. It shows that nitrogen and a transport pathway have reached groundwater in the area; a certified-lab test is still the only way to know a specific private well.

Sources and provenance

What this page rests on

  1. NitrateSmart inventory: 4,473 Texas community water systems with a current nitrate result in the three years from August 9, 2023 to August 9, 2026. Figures count people served by reporting systems, not measured tap exposure.
  2. Nolan BT, Hitt KJ (2006). Vulnerability of Shallow Groundwater and Drinking-Water Wells to Nitrate in the United States. Environmental Science & Technology 40(24):7834–7840.
  3. Dubrovsky NM, and others (2010). Nutrients in the Nation's Streams and Groundwater, 1992–2004. USGS Circular 1350.
  4. Gurdak JJ, Qi SL (2006). Vulnerability of Recently Recharged Ground Water in the High Plains Aquifer to Nitrate Contamination. USGS Scientific Investigations Report 2006-5050.
  5. Scanlon BR, Dutton A, Sophocleous M. Groundwater Recharge in Texas. Texas Water Development Board — playa-focused recharge (0.5–8.6 in/yr) and irrigated recharge (0.6–11 in/yr) versus a near-zero regional background.