Houston water
What Houston's own water report says, and why yours may be different
Numbers here come straight from the City of Houston’s Houston Water Quality Report 2025. They describe the City’s main system. If your water comes from somewhere else, read on.
City of Houston, main system
The 2025 numbers
| What | Reported | In plain terms |
|---|---|---|
| Total hardness (as CaCO3) | 43.5 to 229 mg/L, average 135.5 | about 2.5 to 13.4 grains per gallon, average 7.9 |
| Chloramine (disinfectant) | 0.04 to 4.8 ppm, average 2.8 | measured in the distribution system |
| Total dissolved solids | 146 to 331 ppm, average 260 | everything dissolved in the water |
| Where the water comes from | 90.3% surface water, 9.7% groundwater | Lake Conroe and Lake Houston (San Jacinto River) and Lake Livingston (Trinity River); 104 wells in the Evangeline and Chicot aquifers, deeper than 750 feet |
Source: City of Houston, Houston Public Works, Houston Water Quality Report 2025, Main System (TX1010013). Grains per gallon calculated as mg/L divided by 17.1.
Hardness
An average of 7.9 grains is hard water: enough to leave scale on fixtures and spots on glass. The range matters as much as the average. The lowest sample was soft and the highest was more than five times harder.
Chloramine
The City disinfects with chloramine, a mix of chlorine and ammonia that lasts longer in the pipes than chlorine alone. It does an important job. It is also the taste and smell many people notice, and it is a filtration job, not a softener job.
Two kinds of source
Most of the City’s water is treated lake water; the rest comes from wells deeper than 750 feet. Which mix reaches a given house depends on where it is.
Not on City water?
A lot of northwest Houston is on a MUD
Much of northwest Harris County gets its water from a municipal utility district (MUD), not the City. The North Harris County Regional Water Authority says 143 MUDs take part in its groundwater reduction plan, and it delivers surface water to 61 districts. So neighbors a few miles apart can be on lake water, well water or a mix.
The name on your water bill tells you who your provider is, and every provider publishes an annual water quality report. The surest answer for your house is a test of your own tap.
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