Round Rock and Williamson County hard water guide
Last reviewed: October 24, 2026.
Williamson County sits on limestone, and many of its utilities deliver hard to very hard water. But the numbers differ a lot from one city to the next, and even within a city. This guide pulls the hardness figures from each utility's own report, explains why they vary, and shows how to turn your number into a softener decision.
Hardness by utility
| Utility | Reported hardness | About (gpg) | Main sources (per the utility) | Report |
|---|---|---|---|---|
| Round Rock | Average 258 ppm, range 100–358 (data table); text says 249 mg/L average | 14.5–15.1 average (5.8–20.9 range) | Lake Georgetown, Edwards Aquifer wells, Lake Travis via BCRUA | 2025 CCR |
| Cedar Park | 183 ppm | 10.7 | Lake Travis | 2025 CCR |
| Leander | 194 ppm | 11.3 | Lake Travis intake and Brushy Creek Regional plant | 2024 CCR (the 2025 report has no hardness row) |
| Georgetown | 176–178 mg/L (Lake Georgetown and Southlake plants); 309–320 mg/L (Park and Southside plants) | about 10–11; about 19 (city's figures) | Depends on plant | City knowledge base (historical data) |
| Pflugerville | 201–333 mg/L | 11.7–19.5 | Mainly Lake Pflugerville, some groundwater | 2025 report |
| Hutto | Manville WSC wholesale water: 39.7–346 ppm | 2.3–20.2 | City wells (Carrizo-Wilcox), plus water bought from Taylor and Manville WSC | 2025 CCR |
Grains per gallon are our conversions (ppm ÷ 17.12) except where the utility gives its own. Hutto's 2025 report prints a hardness range only for the Manville WSC water it buys, not for its own wells or for water from Taylor, so treat that row as a partial picture. Pflugerville is mostly in Travis County but sits right on the Round Rock line, so we include it.
On the US Geological Survey's scale, anything over 180 mg/L is "very hard." Round Rock, Pflugerville, the Georgetown well plants and much of Hutto's range are well past that. Cedar Park and Leander sit right at the line.
Why Round Rock water is so hard
Round Rock's 2025 report says it plainly: the city's water "comes from sources that naturally contain dissolved limestone and other mineral-bearing rock formations common throughout Central Texas. As water moves through these formations, it picks up calcium and magnesium minerals." The report calls its 249 mg/L average "very hard water" and notes the minerals "are not harmful to health," though customers "may notice mineral deposits on fixtures, dishes, and appliances."
The wide range (100 to 358 ppm) reflects the mix of sources. Round Rock draws surface water mainly from Lake Georgetown, groundwater from the Edwards Aquifer, and Lake Travis water treated by the Brushy Creek Regional Utility Authority (BCRUA), a regional plant Round Rock shares with Cedar Park and Leander. Which blend reaches your tap can shift through the year.
Cedar Park and Leander are softer mainly because they rely on Lake Travis, which they treat at their own plants and at the BCRUA plant. Austin Water, by contrast, describes a lime softening process at its plants, which helps explain why Austin averages about 5.4 gpg. See our Austin softener guide for that comparison.
Check which utility you're actually on
A Round Rock or Georgetown mailing address doesn't guarantee city water. Parts of the county are served by special utility districts, water supply corporations and MUDs. Look at the name on your water bill, then pull that utility's annual Consumer Confidence Report. Our guide to reading a Texas water quality report shows where the hardness row usually sits.
Do you need a softener?
At 10 to 20 gpg, most of Williamson County is where softeners pay off most, by reducing scale in water heaters, spotting on fixtures and the extra soap hard water needs.
- Round Rock, Pflugerville, Georgetown well plants, much of Hutto: very hard. A salt-based softener is the standard fix if scale and spotting bother you.
- Cedar Park, Leander, Georgetown lake plants: about 10–11 gpg. Hard enough that many homeowners soften, especially with a tankless heater.
- Tankless water heaters: a US Department of Energy Building America guide notes manufacturers may require a softener when supply hardness exceeds 8 to 14 gpg. Every utility in the table above reaches that range, so check your heater's manual and warranty terms.
All of these utilities disinfect with chloramine (Round Rock averaged 2.15 ppm, Cedar Park 3.09 ppm, Leander 2.40 ppm and Hutto 1.54 ppm in their latest reports). A softener doesn't remove chloramine. For taste and smell, see our Texas filtration guide.
Sizing a softener for Williamson County water
Using a common rule of thumb of about 75 gallons per person per day indoors (your water bill gives the real number):
Example, family of four in Round Rock at 15 gpg: 15 × 4 × 75 = 4,500 grains per day, or about 31,500 grains per week. Because Round Rock's range runs up to about 21 gpg, many households size with some margin or test at the tap first. At 21 gpg the same family needs about 6,300 grains per day.
Example, family of four in Cedar Park at 10.7 gpg: 10.7 × 4 × 75 = about 3,210 grains per day, or about 22,500 per week.
Pick a unit whose capacity at an efficient salt setting covers about a week. Headline numbers like "48,000 grain" are usually at maximum salt. The Building America Solution Center explains that an efficiency rating under NSF/ANSI 44 or WQA S-100 requires demand-initiated regeneration, at least 3,350 grains removed per pound of salt, and no more than 5.0 gallons of water per 1,000 grains removed.
Our SoftPro softener guide for Texas homes includes a sizing worksheet and model picks for very hard Central Texas water. That guide contains affiliate links. The same sizing math is worked through for 15–20 gpg water in our San Antonio guide.
Salt-free conditioners at this hardness
University of Nebraska–Lincoln Extension says salt-free devices "do not remove the hardness"; template-assisted crystallization (TAC) turns hardness minerals into tiny crystals that are less likely to stick, and "few conclusive studies confirm the efficiency of these devices for residential use." At Round Rock's hardness, they won't give you soft-feeling water or spot-free glass. If that's what you want, ion exchange is the proven option.
Bottom line
Round Rock averages about 14.5 to 15 gpg and can top 20; Pflugerville, Georgetown's well plants and Hutto run similarly hard, while Cedar Park and Leander are closer to 11. Across most of Williamson County, a properly sized, demand-initiated softener is a common and sensible choice.
Sources
- City of Round Rock, 2025 Consumer Confidence Report
- City of Cedar Park, 2025 Annual Drinking Water Quality Report
- City of Leander, Drinking Water Quality Reports (2024 and 2025 reports)
- City of Georgetown, askGTX: water hardness
- City of Pflugerville, 2025 Water Quality Report (PWS TX2270014)
- City of Hutto, Water Quality (2025 CCR, including Manville WSC and City of Taylor wholesale data)
- US Geological Survey, Hardness of Water
- US Department of Energy, Building America, Measure Guideline: Transitioning to a Tankless Water Heater (IBACOS, 2012)
- Pacific Northwest National Laboratory, Building America Solution Center, Water Softeners
- University of Nebraska–Lincoln Extension, NebGuide G2275: Salt-Free Water "Softener" Options
Related: Frisco, Plano and McKinney water hardness (NTMWD) · Texas water hardness by city · buying a home with an existing softener.
Information only; not plumbing or health advice. For water quality questions, contact your utility.