Measured, not modelled
Measured well-water hardness in Williamson County, Texas: the median of laboratory samples taken at real water wells, in grains per gallon and mg/L as CaCO3, with the number of wells behind the figure.
| Median hardness | 16.4 gpg — about 280 mg/L as CaCO3 |
| Rating | very hard (Water Quality Association scale) |
| Middle half of samples | 11.3–20.2 gpg |
| Wells measured | 430 |
| Laboratory samples | 1,009 |
| Sampled | 1938–2025 |
Source: Texas Water Development Board — Groundwater Database (GWDB). TWDB Groundwater Database (GWDBDownload.zip). These are laboratory results at water wells in the public record — not municipal tap water and not a model. The figure is a county median: individual wells vary, and only a test on the property itself gives its reading. The full table for the state is at well water hardness in Texas, by county; the method is on the methodology page.
Ratings use the Water Quality Association scale, in grains per gallon (gpg); 1 gpg is 17.1 mg/L as CaCO3.
| Rating | Range |
|---|---|
| soft | 0 – 1 gpg |
| slightly hard | 1 – 3.5 gpg |
| moderately hard | 3.5 – 7 gpg |
| hard | 7 – 10.5 gpg |
| very hard | over 10.5 gpg |
Yes — the median of 1,009 laboratory hardness samples from 430 measured wells in Williamson County is 16.4 grains per gallon (about 280 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. The middle half of those samples falls between 11.3 and 20.2 gpg, so individual wells vary widely around the median. Samples span 1938–2025. This is groundwater measured at other wells in the county, not a reading from any one property.
At or above 7 grains per gallon a water softener is the standard treatment; the county median of 16.4 gpg is above that line. Only a test on the property itself confirms the reading and sizes any equipment properly.
430 distinct wells in Williamson County carry a laboratory hardness result in the public record we read; a county is published only when at least 3 do. Nothing here is estimated from municipal tap water.
Selling water treatment here? The newly filed wells in Williamson County are sold as part of the Austin Hill Country territory — one dealer, exclusive.
Built from the same data that qualifies every lead Hard Water Feed sells, and regenerated with it — the figures on this page change only when the underlying public record does.