Austin, TX water hardness: 93 mg/L (5.4 grains per gallon)
Austin Water's own 2025 Water Quality Report gives an average total hardness of 93 mg/L (5.4 gpg) as CaCO3, with a range of 70–126 mg/L. That is moderately hard on the USGS scale. Austin Water prints the figures on page 6 of the report.
Set appliances for 7.4 gpg, the top of Austin Water's 4.1–7.4 gpg range. A home softener is optional, because Austin Water already softens the water at the plant.
What Austin Water's 2025 report says
Total hardness ranged from 70 to 126 mg/L in 2025, with an average of 93 mg/L. Austin Water prints the same figures in grains per gallon.
| Measure | Low | High | Average |
|---|---|---|---|
| Total hardness (as CaCO3), ppm = mg/L | 70 | 126 | 93 |
| Same, in grains per gallon (utility's figures) | 4.1 | 7.4 | 5.4 |
How hard the water is from each treatment plant
Recent readings at the three plants were about 68–75 mg/L, near the low end of the 2025 range. The figures below come from Austin Water's latest monthly and quarterly data.
Austin draws water from the Lower Colorado River (Lake Travis and Lake Austin). It treats the water at three plants: Davis, Ullrich and Handcox. The annual report gives one system-wide figure. Austin Water also posts monthly and quarterly summaries with hardness by plant.
| Plant (treated “tap” water) | Sept 2026 avg (min–max), mg/L | Jul–Sep 2026 avg, mg/L | Jul–Sep 2026 lake water before treatment, mg/L |
|---|---|---|---|
| Davis | 69 (65–72) | 70 | 160 |
| Ullrich | 73 (70–82) | 75 | 162 |
| Handcox | 68 (66–72) | 70 | 155 |
First, the lake water is about twice as hard as what leaves the plants. Austin Water's report says it uses a lime softening step in treatment. Second, recent readings (about 68–75 mg/L) sit near the low end of the 2025 range. Hardness at your tap can change during the year, so use the range, not only the average.
Why other sites show a different number
Other lookup sites show different figures for Austin, some lower and some higher than the 2025 average. A lower figure may match a recent monthly reading, like the 68–75 mg/L plant readings above. Higher figures may come from older data, untreated lake water, or ZIP-code estimates. The numbers here are Austin Water's own, with the report year shown.
What 93 mg/L means at home
The dishwasher level that fits Austin water
Many dishwashers ask for hardness in grains per gallon, or as a level from a table in the manual: choose 7.4 gpg, the high end of the 4.1–7.4 gpg range Austin Water prints. If your machine uses German degrees (°dH), 7.4 gpg is about 7.1 °dH (7.4 × 17.1 = 126.5 mg/L; 126.5 ÷ 17.8 = 7.1, using 1 °dH = 17.8 mg/L).
How to set a softener in Austin
If you already own a softener, program it for 7.4 gpg, the top of Austin Water's 4.1–7.4 gpg range. Then the softener does not run out between regenerations. Austin Water's average is moderately hard, and the utility already softens it at the plant. Whether a home softener is worth it is up to you. Test your tap first.
How much scale kettles, coffee makers and showers get
Moderately hard water leaves some white scale (calcium carbonate) when it is heated. Expect slow build-up in kettles, coffee makers and on shower glass. Descale when you see white crust or the appliance's descale light comes on. USGS says hardness “is not a health concern, but it can be a nuisance.”
How to find the hardness at your own tap
Use a hardness test kit, or call Austin Water's Water Quality Manager at 512-972-0012 (listed in the report). The utility's figure is for the whole system, not your address. An apartment softener, water heater or old pipes can change what comes out of your tap.
Sources
- Austin Water, 2025 Water Quality Report (PDF), page 6 “Hardness” table and page 16 FAQ: https://austin.widen.net/view/pdf/olm10prt8x/AW_WQR_Report_2025.pdf
- Austin Water, Water Quality Reports page (same 2025 table in HTML): https://www.austintexas.gov/water/programs/water-quality-reports
- Austin Water, Water Quality Summaries (monthly and quarterly, by plant): https://www.austintexas.gov/water/water-quality-summaries; September 2026; Q3 2026
- USGS Water Science School, Hardness of Water (class limits): https://www.usgs.gov/water-science-school/science/hardness-water