How hard is the water in the Highland Lakes and North Austin?
Every water supply in our service area with a published figure is hard. City water runs from 161 mg/L in Liberty Hill (9.4 grains per gallon) to 258 mg/L in Round Rock (15.1). Private wells run harder, with county medians from 282 mg/L in Williamson County to 377 mg/L in Lampasas County (16.5 to 22 grains per gallon).
Hardness of city water, by town
Figures are each utility’s reported average, in milligrams per liter of calcium carbonate, with the grains-per-gallon equivalent. Where a town has no figure, it’s because the utility doesn’t publish one or we couldn’t verify it.
| Town | Source | mg/L | gpg | Class |
|---|---|---|---|---|
| Round Rock | Lake Georgetown, the Edwards Aquifer and Lake TravisCity of Round Rock 2025 water quality report, range 100–358 mg/L | 258 | 15.1 | Very hard |
| Leander | Lake TravisCity of Leander water quality report | 194 | 11.3 | Very hard |
| Marble Falls | Lake Marble FallsCity of Marble Falls water quality report | 185 | 10.8 | Very hard |
| Cedar Park | Lake TravisCity of Cedar Park water quality report | 183 | 10.7 | Very hard |
| Horseshoe Bay | Lake LBJCity of Horseshoe Bay 2019 water quality report | 175 | 10.2 | Hard |
| Liberty Hill | water purchased from Leander (Lake Travis)City of Liberty Hill 2023 water quality report | 161 | 9.4 | Hard |
| Burnet | The City of Burnet blends Inks Lake water with groundwater and does not publish a hardness figure in its water quality report. | |||
| Georgetown | Georgetown’s water quality report does not publish a hardness figure. Its Lake Georgetown water is treated by the City of Round Rock. | |||
| Granite Shoals | We have not been able to verify a published hardness figure for Granite Shoals city water. | |||
| Kingsland | We have not been able to verify a published hardness figure for the Kingsland water supply corporation. | |||
| Spicewood | Spicewood is unincorporated. Homes are served by several small water systems or private wells, and we have not verified a single hardness figure. | |||
| Lampasas | We have not been able to verify a published hardness figure for Lampasas city water. | |||
How hard are private wells in each county?
Wells are not treated by a utility, and they run roughly twice as hard as city water here. These are the median results of sampled wells in the Texas Water Development Board’s groundwater database.
| County | Median mg/L | gpg | Wells testing very hard | Residents on wells |
|---|---|---|---|---|
| Lampasas County | 377 | 22 | 96% | 4% |
| Burnet County | 369 | 21.6 | 99% | 23% |
| Llano County | 328 | 19.2 | 93% | 9% |
| Williamson County | 282 | 16.5 | 78% | 2% |
Which supplies are over the tankless warranty limit?
Noritz, Navien and Rheem exclude scale damage on tankless water heaters above 200 mg/L (about 11.7 grains per gallon), marked by the dashed line. Bars in red are over it.
If you’re on city water, your utility publishes its figure once a year in its water quality report. Most towns with a published figure sit just under the tankless line, so tankless works with yearly descaling. Round Rock is over it.
If you’re on a private well, nobody tests it for you. The median well in every county we have data for is well over the line, so plan on a softener before a tankless unit. We test your water before recommending either.
Hard water questions we hear most
Find answers to common plumbing and HVAC questions from our expert team.
The U.S. Geological Survey classes water by its dissolved calcium and magnesium, measured as calcium carbonate: 0–60 mg/L is soft, 61–120 is moderately hard, 121–180 is hard, and anything over 180 is very hard. One grain per gallon equals 17.1 mg/L.
Yes. Hardness is not a health concern. The problems are practical: scale inside water heaters and fixtures, spots on glass, and soap that won’t lather.
Noritz, Navien and Rheem all exclude scale damage on tankless water heaters when the water is harder than 200 mg/L, about 11.7 grains per gallon. Round Rock city water and the median private well in every county we have data for are over that line.
Their utilities don’t publish one. Georgetown’s water quality report has no hardness figure; its Lake Georgetown water is treated by the City of Round Rock. The City of Burnet blends Inks Lake water with groundwater and doesn’t publish hardness either. If you live there, we can test your water at your home.
Have a question that's not listed here? Give us a call and we'll be happy to help.
Sources
- Each city’s annual water quality (Consumer Confidence) report, checked August 2026.
- Texas Water Development Board Groundwater Database, median of sampled private wells by county; private-well share from USGS (2015).
- U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates (tables B25034, B25035, B25003).
- Noritz, Navien and Rheem tankless warranty terms, which exclude scale damage above 200 mg/L.
- Hardness classes: U.S. Geological Survey. Conversion: 1 grain per gallon = 17.1 mg/L.
Figures checked August 25, 2026.
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