Measured, not modelled
Measured well-water hardness in Tom Green 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 | 27.7 gpg — about 474 mg/L as CaCO3 |
| Rating | very hard (Water Quality Association scale) |
| Middle half of samples | 17–51.8 gpg |
| Wells measured | 228 |
| Laboratory samples | 362 |
| Sampled | 1950–2023 |
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 362 laboratory hardness samples from 228 measured wells in Tom Green County is 27.7 grains per gallon (about 474 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. The middle half of those samples falls between 17 and 51.8 gpg, so individual wells vary widely around the median. Samples span 1950–2023. 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 27.7 gpg is above that line. Only a test on the property itself confirms the reading and sizes any equipment properly.
228 distinct wells in Tom Green 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 in Texas? The new wells behind these figures are sold by territory — well water leads in Texas.
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.