If you've moved to Central Texas from almost anywhere else, you probably noticed it in the first week: white crust on the shower head, soap that refuses to lather, glassware that comes out of the dishwasher cloudy. That's hard water — dissolved calcium and magnesium picked up from limestone.
But here's what most water-treatment websites get wrong, and we'd rather tell you the truth than sell you on a scary number: the City of Austin's treated water is not as hard as people assume. The homes around Austin, on the other hand, often are — sometimes dramatically so.
Austin Water publishes its hardness figures every year in its Consumer Confidence Report. The most recent numbers:
| Measurement | ppm (mg/L) | Grains per gallon |
|---|---|---|
| Austin average | 93 | 5.4 gpg |
| Reported low | 70 | 4.1 gpg |
| Reported high | 126 | 7.4 gpg |
Source: Austin Water Consumer Confidence Report. 1 grain per gallon = 17.1 mg/L.
On the standard USGS scale, that puts Austin in the “moderately hard” band — not “hard,” and not “very hard.”
The reason is that Austin softens its water at the treatment plant. Austin's supply is surface water from the Colorado River — Lake Austin and Lake Travis, not the Edwards Aquifer, as is often assumed. Raw water arriving at the plants runs roughly 160–215 ppm (9–12.5 gpg). Austin runs it through a conventional lime softening process, which strips out a large share of the calcium before the water ever reaches your street.
Neighboring utilities largely don't do this. Cedar Park and Leander pull from the same Highland Lakes system, deliver it without that softening step, and land at nearly double Austin's hardness.
This is the table that actually matters, because most of the homes we install in are not on Austin Water:
| City / Utility | ppm | gpg | Classification |
|---|---|---|---|
| Austin | 93 | 5.4 | Moderately hard |
| Georgetown | ~90 | ~5.3 | Moderately hard |
| Waco | ~131 | ~7.6 | Hard |
| Temple | 149 | 8.7 | Hard |
| Pflugerville | ~168 | ~9.8 | Hard |
| Cedar Park | 183 | 10.7 | Very hard |
| Leander | 194 | 11.3 | Very hard |
| Round Rock | 249 | 14.6 | Very hard |
| New Braunfels | 258 | ~15.1 | Very hard |
| San Marcos | 283 | 16.5 | Very hard |
| Brushy Creek MUD | 115–205 | 6.7–12.0 | Varies weekly |
| Hutto | 42–369 | 2.4–21.6 | Varies by source |
Figures from each utility's published water quality report. Waco and Pflugerville values are calculated from published calcium and magnesium levels. Temple's figure reflects an older sample year. Where a utility blends sources, hardness moves around — see below.
This is the single most important thing on this page. A large share of homes with an Austin mailing address are served by a MUD, a water supply corporation, or a neighboring city — not by Austin Water. Two houses fifteen minutes apart can differ by 10 grains per gallon. Your utility, not your ZIP code, determines your water.
The U.S. Geological Survey classifies hardness like this:
| Classification | mg/L (ppm) | Grains per gallon |
|---|---|---|
| Soft | 0–60 | 0–3.5 |
| Moderately hard | 61–120 | 3.6–7.0 |
| Hard | 121–180 | 7.1–10.5 |
| Very hard | Over 180 | Over 10.5 |
USGS publishes this scale in mg/L; the grains-per-gallon column is a straight unit conversion at 17.1 mg/L per grain.
Rain falling on the Edwards Plateau picks up carbon dioxide and becomes mildly acidic. That weak carbonic acid dissolves the limestone it filters through — and limestone is calcium carbonate. The water arrives at your tap carrying that dissolved mineral load.
The Edwards Aquifer is karst limestone: porous, honeycombed rock. The Texas Water Development Board describes water from the Edwards–Trinity system as “generally a hard, calcium bicarbonate type.” That geology is why utilities drawing on Edwards groundwater — San Marcos, New Braunfels, parts of Round Rock — sit at the top of the table above.
Utilities that blend multiple sources see real swings through the year. Brushy Creek MUD publishes hardness weekly and advises residents to set their softener slightly above the current reading — in one recent year its water ranged from 115 to 205 ppm. Hutto blends three different sources and has reported everything from 42 to 369 ppm. Round Rock mixes Lake Georgetown surface water with Edwards Aquifer groundwater, so the number depends on which source is carrying the load that week.
A properly sized softener accounts for the high end of that range, not the average. Undersize it against a seasonal peak and you'll get hard water breakthrough right when you least expect it.
If you're on Austin Water, your water is moderately hard — a softener is a comfort-and-appliance-life decision, not an emergency. If you're in Round Rock, Cedar Park, Leander, San Marcos, New Braunfels, or on a MUD or well, you're likely in genuinely hard to very hard territory, and the case is much stronger. Either way, the right move is the same: test your actual water before you buy anything.
We'll do that third step for you free, at your address, with no obligation and no pressure — and if your water genuinely doesn't need treatment, we'll tell you that.
We'll test your water at your address — free, no obligation — and show you exactly what you're dealing with before anyone talks about equipment.