Measured, not modelled
Measured well-water hardness in Duval 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 | 14.9 gpg — about 255 mg/L as CaCO3 |
| Rating | very hard (Water Quality Association scale) |
| Middle half of samples | 7–29.3 gpg |
| Wells measured | 245 |
| Laboratory samples | 487 |
| Sampled | 1913–2025 |
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 487 laboratory hardness samples from 245 measured wells in Duval County is 14.9 grains per gallon (about 255 mg/L as CaCO3), which is “very hard” on the Water Quality Association scale. The middle half of those samples falls between 7 and 29.3 gpg, so individual wells vary widely around the median. Samples span 1913–2025. 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 14.9 gpg is above that line. Only a test on the property itself confirms the reading and sizes any equipment properly.
245 distinct wells in Duval 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.