Texas water hardness by city
Three Texas utilities supply three very different kinds of water. Austin softens at the plant, San Antonio pumps water from limestone aquifers, and Houston blends lake water with well water.
| City (utility) | Average | Range | USGS class | Source and year |
|---|---|---|---|---|
| Austin (Austin Water) | 93 mg/L · 5.4 gpg | 70–126 mg/L · 4.1–7.4 gpg | Moderately hard | 2025 Water Quality Report |
| San Antonio (SAWS) | not published | 15–20 gpg · ≈ 257–342 mg/L* | Very hard | SAWS FAQ, undated (2026 report has no hardness) |
| Houston (Main System) | 135.5 mg/L · ≈ 7.9 gpg* | 43.5–229 mg/L · ≈ 2.5–13.4 gpg* | Hard (range: soft to very hard) | 2025 Water Quality Report |
Quick settings guide
| City | Softener setting without a test | Dishwasher |
|---|---|---|
| Austin | At least 7.4 gpg (the top of Austin's range) | Level for about 5–7 gpg |
| San Antonio | 20 gpg | Highest or second-highest level |
| Houston (Main) | Test first; range is 2.5–13.4 gpg | Level for about 7–9 gpg, adjust by results |
These are starting points based on the utility figures. A test at your own tap is more accurate than any city-wide number.
Sources
- Austin Water, 2025 Water Quality Report: https://austin.widen.net/view/pdf/olm10prt8x/AW_WQR_Report_2025.pdf
- SAWS, Water Quality FAQs: https://www.saws.org/your-water/water-quality/saws-water-quality-concerns/faqs/
- City of Houston, Water Quality Report 2025: https://houstonpublicworks.org/sites/g/files/nwywnm456/files/doc/003_2025_houston_water_quality_report.pdf
- USGS, Hardness of Water: https://www.usgs.gov/water-science-school/science/hardness-water