San Antonio, Texas
| Contaminant | Detected | EPA limit | EWG guideline | Status |
|---|---|---|---|---|
| Total Hardness (as CaCO3) | 280 mg/L | — | — | — |
| Total Trihalomethanes (TTHMs) | 18.5 ppb | 80 ppb | 0.8 ppb | 23× EWG |
| Haloacetic Acids (HAA5) | 12.8 ppb | 60 ppb | 0.1 ppb | 128× EWG |
| Fluoride | 0.58 mg/L | 4 mg/L | 0.7 mg/L | Within guideline |
| Lead | 1 ppb | 15 ppb | 0.5 ppb | 2× EWG |
Context
San Antonio has some of the hardest water in the US at 280 mg/L (about 16 grains per gallon), classified as 'very hard.' The Edwards Aquifer's limestone geology produces high calcium and magnesium content that causes significant scale buildup.
The Edwards Aquifer source water is exceptionally clean — naturally filtered through limestone — resulting in relatively low contaminant levels compared to cities using surface water. This is one of the cleaner major city water supplies in the US.
Water conservation is a major concern due to aquifer sustainability. SAWS has implemented aggressive conservation programs and is diversifying supply sources to reduce Edwards Aquifer dependence.
Common questions
Is San Antonio water safe to drink?
Yes — San Antonio has some of the cleanest source water of any major US city. The Edwards Aquifer produces naturally filtered groundwater with low contaminant levels. The main practical issue is extreme water hardness (280 mg/L), which isn't a health hazard but causes scale buildup and appliance damage. A water softener is the most common home water upgrade in San Antonio.
Why is San Antonio water so hard?
San Antonio's water comes from the Edwards Aquifer, a massive limestone formation. As water percolates through hundreds of feet of limestone, it dissolves calcium and magnesium — the minerals that cause water hardness. At 16+ grains per gallon, San Antonio water is classified as 'very hard.' A whole-house water softener is the standard solution.
San Antonio is a tale of two stories: the source water is excellent (Edwards Aquifer groundwater is naturally filtered and very clean), but the extreme hardness is a practical headache for every household. A whole-house water softener is the single most impactful upgrade for San Antonio homes, protecting appliances and plumbing while improving soap performance and skin feel.
the Edwards Aquifer — a massive limestone aquifer that naturally filters water through hundreds of feet of rock, producing exceptionally clean groundwater
This data reflects system-wide testing. Your home's plumbing may add or reduce contaminants.
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