San Antonio, TX water hardness
San Antonio Water System (SAWS) publishes a hardness range of 15 to 20 grains per gallon for its system, on the page cited below. At 17.1 mg/L per grain that is 256.5 to 342 mg/L. On the USGS scale that is very hard water.
The published figure, exactly as it appears
This is the hardness line transcribed from the source, with nothing added:
The typical hardness in the water provided by SAWS ranges from 15 to 20 gpg (grains per gallon).
San Antonio Water System (SAWS)
Units as published: gpg (grains per gallon). What kind of figure it is: a range with no average. Retrieved 2026-10-16.
San Antonio hardness in mg/L and grains per gallon
Water-quality reports use mg/L (identical to ppm). Softener instructions and plumbing specifications use grains per gallon. Both are below. Where a figure is our arithmetic rather than the utility's own number, it says so.
| Figure | mg/L (ppm) | Grains per gallon | Whose number |
|---|---|---|---|
| Low end of published range | 256.5 | 15 | gpg published, mg/L is our conversion |
| High end of published range | 342 | 20 | gpg published, mg/L is our conversion |
| Plotted on the scale above | 299.3 | 17.5 | midpoint of the published gpg range, converted at 17.1 mg/L per gpg; the gpg here is our conversion at 17.1, so it can differ slightly from a utility’s own rounded gpg figure |
The conversion, both ways: gpg = mg/L ÷ 17.1 and mg/L = gpg × 17.1. Worked for this system: 299.3 ÷ 17.1 = 17.5 gpg. The converter does °dH and °f as well, and why the factor is 17.1 explains where the number comes from.
What this figure does not tell you
Service area and source water
| Utility | San Antonio Water System (SAWS) |
|---|---|
| Public water system ID | TX0150018 |
| Service area as published | The SAWS main system. SAWS also publishes separate reports for its Castle Hills, Geronimo Forest, Mountain Laurel, Northeast and Texas Research Park systems, which this page does not cover. |
| Source water | Groundwater from the Edwards, Carrizo and Simsboro aquifers, and in some areas surface water from Canyon Lake (per the 2026 SAWS Main System report). |
Provenance of every number on this page
| Source document | SAWS Water Quality FAQs, 'What is hardness?' |
|---|---|
| Source URL | https://www.saws.org/your-water/water-quality/saws-water-quality-concerns/faqs/ |
| Published by | San Antonio Water System |
| Report year | Not stated on the source page |
| Year note | SAWS states this figure as a typical range on its own Water Quality FAQs page, with no sampling year attached. The page's modified-time metadata read 2024-05-24 on the retrieval date. The 2026 SAWS Main System Water Quality Report (PWS ID TX 0150018, analyses using 2025 data) was also read on 2026-10-16 and carries no hardness line: it states that secondary constituent results are available on Texas Drinking Water Watch instead. |
| Retrieved | 2026-10-16 |
| Classification bands | USGS Water Science School, retrieved 2026-10-16 |
Notes the report forces on this page
- This is the only SAWS utility figure on this site published in grains per gallon rather than mg/L, so the mg/L figures shown for San Antonio are our conversion at 17.1 mg/L per gpg, not SAWS numbers.
- SAWS describes the figure as typical hardness, not as a measured annual average or a sampling range, and attaches no year to it.
- Other report years checked on 2026-10-16: 2026 (no hardness line).
If you are sizing a softener for San Antonio water
At 17.5 gpg, the sizing arithmetic starts from your household's water use, not from the hardness alone. The calculator below is pre-filled with this system's figure and every other input is an editable assumption.
Whether a softener is worth installing at this hardness is a judgement, not arithmetic, and it is not one this site makes for you. Nothing here has been tested by the author.
Where San Antonio sits against other verified systems
- Portland, OR 9 mg/L 0.5 gpg Soft
- Boston, MA 16 mg/L 1 gpg Soft
- Manchester, NH 17.9 mg/L 1 gpg Soft
- New York, NY 32 mg/L 2 gpg Soft
- Austin, TX 93 mg/L 5.4 gpg Moderately hard
- Denver, CO 105 mg/L 6.1 gpg Moderately hard
- Phoenix, AZ 237 mg/L 13.9 gpg Very hard
- Las Vegas, NV 280 mg/L 16 gpg Very hard
- San Antonio, TX 299.3 mg/L 17.5 gpg Very hard
- Indianapolis, IN 317 mg/L 19 gpg Very hard
mg/L as calcium carbonate. Each classification band is drawn the same width, so the axis is not linear in mg/L.
Systems with similar published hardness
- Indianapolis, IN Citizens Energy Group (Indianapolis), 317 mg/L (18.5 gpg)
- Las Vegas, NV Las Vegas Valley Water District, 280 mg/L (16.4 gpg)
- Phoenix, AZ City of Phoenix Water Services Department, 237 mg/L (13.9 gpg)
- Denver, CO Denver Water, 105 mg/L (6.1 gpg)
All 10 verified systems How to find hardness in your own utility's report If you are on a well instead