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Does Houston Have Hard Water?

By Marcus Webb, CWS| Updated October 2026

Short answer: yes, on average, but it varies a lot. The City of Houston's 2025 Water Quality Report lists total hardness in the Main System from 43.5 to 229 mg/L, averaging 135.5 mg/L (about 7.9 grains per gallon) (Houston Public Works). That average is in the USGS "hard" range of 121 to 180 mg/L, but depending on where and when you sample, Houston water can be anywhere from soft to very hard. The Main System, which serves about 2.97 million customers, disinfects with chloramine.

Kitchen faucet with mineral spots, with close-ups of a cloudy glass, a scaled pot and spotty dishes — Illustration: common signs of hard water in a kitchen: spotty fixtures, cloudy glasses, scaled pots and dishes.

Houston Hardness by Water System

Houston Public Works runs six water systems, and its 2025 report lists hardness (as calcium carbonate) for each:

System	Source	Total Hardness (mg/L)	Grains per Gallon	Disinfectant
Main System (most of Houston)	90.3% surface water, 9.7% groundwater	43.5 to 229, average 135.5	2.5 to 13.4, average 7.9	Chloramine
Kingwood	Groundwater (16 wells)	124 (single sample)	7.3	Chlorine
Willow Chase	Groundwater (5 wells)	160 to 167, average 163.5	9.4 to 9.8	Chlorine
District 73	Groundwater (2 wells)	97.4	5.7	Chlorine
District 82	Groundwater (2 wells)	107	6.3	Chlorine
Belleau Woods	Purchased from the City of Humble	129	7.5	Chloramine

From the Houston Water Quality Report 2025 (Houston Public Works). Some smaller-system figures come from a single sample or from reduced monitoring in an earlier year, as footnoted in the report. Grains per gallon calculated at 17.1 mg/L per grain. Classes from USGS: 61 to 120 moderately hard, 121 to 180 hard, over 180 very hard.

Not sure which system serves you? Most Houston addresses are on the Main System. Kingwood, Willow Chase, Districts 73 and 82 and Belleau Woods are smaller systems with their own sections in the same report. If your water comes from a municipal utility district (MUD) or another provider rather than the City, that provider publishes its own report. All City reports are on the Houston Public Works water quality page. See our water hardness scale for what the numbers mean.

Why Houston Hardness Varies

The report explains that Houston produces water from both surface water (the Trinity River and Lake Livingston, and the San Jacinto River with Lake Conroe and Lake Houston) and groundwater from the Chicot and Evangeline aquifers. The Main System averages about 500 million gallons a day, about 90% from surface water and the rest from 104 wells.

Surface water and groundwater have different mineral content, and the mix reaching your tap depends on which treatment plant or well feeds your area and on the season. That is why a single Main System covers everything from 43.5 mg/L (soft) to 229 mg/L (very hard). The practical takeaway: a citywide average does not tell you your number. Test your own tap with hardness test strips a few times a year before buying equipment; our testing guide shows how.

Chloramine vs Chlorine

The Main System and Belleau Woods report chloramines as their disinfectant (Main System distribution average 2.8 ppm). Kingwood, Willow Chase and Districts 73 and 82 report chlorine. This matters when choosing filters:

Drinking water: chloramine reduction is a separate NSF/ANSI 42 claim. Filters such as the 3M Aqua-Pure 3MDW301 are listed for it; see our under sink filter guide.
Shower filters: NSF/ANSI 177, the shower filter standard, covers free chlorine. Most shower filters are not certified for chloramine, so expect less effect on chloramine taste or smell. See do shower filters work?

Lead and Your Service Line

At customer taps in the Main System, the 2025 report says 90% of lead samples were below 5.1 ppb, with no samples above the 15 ppb action level. Lead mainly comes from service lines and home plumbing, and the City is inventorying service line materials across its six systems; the report links an online map where you can check your address and self-report if your line is listed as unknown. The report recommends a filter certified to reduce lead if you are concerned, using only cold water for drinking and cooking, and flushing your tap before use. Houston Water also offers free lead and copper testing to qualifying homes through a survey linked in the report.

For certified lead filters, see our under sink, countertop and pitcher guides.

What Houston Water Does at Home

At an average near 8 grains per gallon, most Houston homes on the Main System will see the classic hard water signs over time: white crust on faucets and shower heads, spots on glasses, soap scum on shower doors and scale in kettles and coffee makers. Homes on the harder end, like Willow Chase at about 9.5 gpg or Main System areas that reach 229 mg/L, will see more of it. Some people also notice drier skin and duller hair; see hard water and skin and hard water and hair.

Tankless water heater owners should note that the Main System maximum of 229 mg/L is above Rinnai's 200 mg/L water quality guideline; see tankless scale prevention.

Best Fixes for Houston Homes

Test your tap so you size equipment to your water, not the citywide average.
Homeowners: a water softener is the whole-house fix. At 8 gpg and 300 gallons a day, a household removes about 2,400 grains a day, so a 32,000-grain unit like the SpringWell SS1 would regenerate roughly every 11 to 13 days, depending on the reserve setting. See best water softeners, cost and installation.
Renters: a chelating shampoo once a week or two for hair, and regular vinegar or citric acid descaling; see how to remove limescale.
Drinking water: on the Main System, choose a filter certified for chloramine if taste bothers you, and for lead if your home has older plumbing.

Check Hardness Test Strips on Amazon