What Harris County Wells Usually Need
Hard water with iron: 7.5 gpg. The median Harris well is 7.5 gpg hard, and 46% of tested wells carry enough iron (over 0.3 ppm) to stain fixtures.
Is it safe? Usually, going by local records, but confirm with a yearly bacteria and nitrate test.
Typical treatment, in plumbing order:
- A whole-house sediment filter first, so sand and scale do not foul the stages after it.
- A dedicated iron filter if your well is among the 46% over 0.3 ppm, installed ahead of any softener.
- A 24,000-grain softener for a family of four at 7.5 gpg.
See how these stages fit together. Your own test result decides the final list.
Not sure what to install? Get a filter recommendation for Harris County homesOn city or county water instead? Your utility publishes an annual water quality report; this page covers private wells. Find your utility's report
On this page (10 sections)
Getting Your Well Tested in Harris County
- Harris County Public Health: 713-439-6000, 2223 West Loop South, Houston, TX 77027. Drinking water program page
- Certified labs: TCEQ accredited lab search
- Free or low-cost testing: Texas Well Owner Network screenings (Texas A&M AgriLife)
Call before you go; hours and fees change.
What Are You Noticing in Your Water?
Confirm with a lab test before buying equipment.
Explore Texas Interactive Map
Explore Harris County and nearby counties
Nearly all of Harris County is served by public water systems; EPA estimates only 6% of homes (about 104,731) use a private well. (EPA 2020 domestic water source estimates, 2020)
Aquifers and Well Depth in Harris County
The Gulf Coast aquifer underlies the whole of Harris County. (TWDB aquifer maps)
All 399 domestic wells that TWDB has assigned to an aquifer here draw from the Gulf Coast. (TWDB Groundwater Database)
The median domestic well is 265 feet deep, and half of them fall between 220 and 320 feet. Based on 8,183 well records, 2001-2026. (TWDB drillers reports)
What Is in Harris County Well Water
One result per domestic well (the most recent) from TWDB records, with nitrate limited to 1990 and later.
Tests for fluoride mostly came back under the EPA limits.
Most wells produce hard water: the median is 7.5 grains per gallon (128 mg/L), softer than the Texas median of 16.1 gpg. Based on 42 domestic wells, 1933-2009, most recent sample 2009.
Taste and staining problems come mainly from iron (46% of domestic wells over EPA's 0.3 mg/L secondary standard) and total dissolved solids (18% of domestic wells over EPA's 500 mg/L secondary standard).
Among its neighbors, the county's median hardness of 7.5 gpg is below Fort Bend (14.7 gpg), Brazoria (10.2 gpg) and Chambers (9.6 gpg) and above Liberty (7.1 gpg). That is the 149th highest of 200 Texas counties with enough data.
| Parameter | Median | Above limit | Tested | Texas | U.S. |
|---|---|---|---|---|---|
| FluorideEPA limit 4 mg/L | 0.2 mg/L | 0% | 32, 1939-2026, most recent sample 2026 | 4% | |
| IronEPA secondary 0.3 mg/L | 0.1 mg/L | 46% | 24, 1933-2026, most recent sample 2026 | 20% | 19% |
| Hardnesshard above 120 mg/L | 7.5 gpg | 50% | 42, 1933-2009, most recent sample 2009 | 76% | 60% |
| Total dissolved solidsEPA secondary 500 mg/L | 302 mg/L | 18% | 38, 1933-2009, most recent sample 2009 | 56% | 15% |
| ChlorideEPA secondary 250 mg/L | 43.5 mg/L | 9% | 45, 1933-2026, most recent sample 2026 | 22% | |
| SulfateEPA secondary 250 mg/L | 4 mg/L | 0% | 43, 1933-2026, most recent sample 2026 | 19% | |
| pHbelow 6.5 is corrosive | 7.4 pH units | 0% | 30, 1960-2026, most recent sample 2026 | 4% |
"Above limit" counts domestic wells over the listed limit; the U.S. share comes from USGS domestic well sampling, 1991-2004.(TWDB Groundwater Database) (USGS Circular 1332)
Not enough local tests to give a percentage for arsenic (12) and manganese (10).
EPA puts the county in radon Zone 3, the lowest for indoor air; test the house either way. (EPA Map of Radon Zones)
Where Private Wells Are Common in Harris County
72% of the county's well-supplied homes are outside any town or named community, in rural and unincorporated areas. (EPA 2020 domestic water source estimates, 2020)
- Aldine (unincorporated community): about 3,020 homes on wells, 64% of housing
- Spring (unincorporated community): about 3,007 homes on wells, 14% of housing
- Taylor Lake Village: about 947 homes on wells, 67% of housing
EPA 2020 block-group estimates with 2020 Census housing counts; not exact counts.
Testing Your Well in Harris County
For a Harris well, ask the lab for coliform bacteria, nitrate, total dissolved solids, pH, iron and hardness. The first four are EPA's yearly basics; the rest come from the county records above. (EPA) Not sure what to order? Read which well water test to buy.
- Local health department: Harris County Public Health, 2223 West Loop South, Houston, TX 77027, 713-439-6000
- Labs: TCEQ accredited lab search
- Screening: Texas Well Owner Network
Texas Rules for Private Wells
No Texas agency checks the water in a household well, though a TDLR license is required to drill one or set its pump. (TCEQ, TDLR)
In Harris County, the Harris-Galveston Subsidence District sets well registration, spacing and pumping limits; check with it before drilling.
Frequently Asked Questions
How hard is well water in Harris County?
The median domestic well tested at 7.5 grains per gallon (128 mg/L as calcium carbonate), based on 42 domestic wells. That is hard enough that most households use a water softener.
How deep are private wells in Harris County?
Drillers report a median of 265 feet (most from 220 to 320 feet) across 8,183 records.
Is well water in Harris County safe to drink?
Usually, going by public records, which rarely show health limits exceeded here. Still test every year for bacteria, nitrate, dissolved solids and pH, because every well differs.
Nearby Counties
Brazoria County Chambers County Fort Bend County Galveston County Liberty County Montgomery County Waller County
Sources and Data Notes
TWDB Groundwater Database, TWDB drillers reports, TWDB aquifer maps, TWDB district records, EPA 2020 domestic water source estimates, 2020 Census, EPA Map of Radon Zones, USGS Circular 1332, Texas DSHS, TCEQ, TDLR, EPA. Retrieved 2026-10-26.