San Antonio, Texas Tap Water Quality Report
Serving utility: San Antonio Water System
Updated March 2026 • Data from EWG Tap Water Database & EPA SDWIS
High Priority Concerns
San Antonio tap water has 15 contaminants exceeding EWG health guidelines, including Haloacetic acids (HAA9), Total trihalomethanes (TTHMs), Bromochloroacetic acid. Additionally, 14 known or suspected carcinogens were detected, including Haloacetic acids (HAA9), Total trihalomethanes (TTHMs), Bromodichloromethane.
Water Provider Information
Contaminants Detected
| Contaminant | Detected Level | EWG Guideline | Legal Limit | Status |
|---|---|---|---|---|
| Haloacetic acids (HAA9) carcinogen | 9.67 ppb | 0.06 ppb | No legal limit | Above guideline |
| Total trihalomethanes (TTHMs) carcinogen | 22.90 ppb | 0.15 ppb | 80 ppb | Above guideline |
| Bromochloroacetic acid | 2.12 ppb | 0.02 ppb | No legal limit | Above guideline |
| Dibromoacetic acid | 2.41 ppb | 0.03 ppb | No legal limit | Above guideline |
| Bromodichloromethane carcinogen | 4.42 ppb | 0.06 ppb | No legal limit | Above guideline |
| Haloacetic acids (HAA5) carcinogen | 5.76 ppb | 0.10 ppb | 60 ppb | Above guideline |
| Dibromochloromethane carcinogen | 5.55 ppb | 0.10 ppb | No legal limit | Above guideline |
| Nitrate and nitrite carcinogen | 2.01 ppm | 0.14 ppm | 10 ppm | Above guideline |
| Dichloroacetic acid carcinogen | 2.05 ppb | 0.20 ppb | No legal limit | Above guideline |
| Nitrate carcinogen | 1.42 ppm | 0.14 ppm | 10 ppm | Above guideline |
| Chloroform carcinogen | 2.82 ppb | 0.40 ppb | No legal limit | Above guideline |
| Chromium (hexavalent) carcinogen | 0.14 ppb | 0.02 ppb | No legal limit | Above guideline |
| Radium, combined (-226 and -228) | 0.34 pCi/L | 0.05 pCi/L | 5 pCi/L | Above guideline |
| Bromoform carcinogen | 2.95 ppb | 0.50 ppb | No legal limit | Above guideline |
| Trichloroacetic acid carcinogen | 0.43 ppb | 0.10 ppb | No legal limit | Above guideline |
| 1,4-Dioxane carcinogen | 0.01 ppb | 0.35 ppb | No legal limit | Below guideline |
| 2-methyl-1-propene | 5 ppb | N/A | No legal limit | Below guideline |
| Barium | 62 ppb | 700 ppb | 2,000 ppb | Below guideline |
| Chlorate | 6.27 ppb | 210 ppb | No legal limit | Below guideline |
| Chromium (total) | 0.24 ppb | N/A | 100 ppb | Below guideline |
| Cobalt | 0.01 ppb | 70 ppb | No legal limit | Below guideline |
| Fluoride | 0.43 ppm | N/A | 4 ppm | Below guideline |
| Hexadecanoic acid | 3.91 ppb | N/A | No legal limit | Below guideline |
| Lithium | 9.45 ppb | N/A | No legal limit | Below guideline |
| Manganese | 0.30 ppb | 100 ppb | No legal limit | Below guideline |
| Molybdenum | 1.04 ppb | 40 ppb | No legal limit | Below guideline |
| Monobromoacetic acid | 0.03 ppb | 25 ppb | No legal limit | Below guideline |
| Monochloroacetic acid | 0.09 ppb | 53 ppb | No legal limit | Below guideline |
| Octadecanoic acid | 6.15 ppb | N/A | No legal limit | Below guideline |
| Perfluorobutane sulfonate (PFBS) | 0.09 ppt | 2,000 ppt | No legal limit | Below guideline |
| Perfluorobutanoic Acid (PFBA) | 0.54 ppt | 1,000 ppt | No legal limit | Below guideline |
| Perfluoropentanoic Acid (PFPeA) | 0.08 ppt | 1,000 ppt | No legal limit | Below guideline |
| Selenium | 0.10 ppb | 30 ppb | 50 ppb | Below guideline |
| Strontium | 0.81 ppb | 1,500 ppb | No legal limit | Below guideline |
| Thallium | 0.05 ppb | 0.10 ppb | 2 ppb | Below guideline |
| Uranium carcinogen | 0.14 pCi/L | 0.43 pCi/L | 20 pCi/L | Below guideline |
| Vanadium | 2.72 ppb | 21 ppb | No legal limit | Below guideline |
| Xylenes (total) | 0.01 ppb | 1,800 ppb | 10,000 ppb | Below guideline |
Health Context
Haloacetic acids (HAA9) carcinogen
Exposure to elevated levels of this contaminant may pose health risks. See EWG and EPA guidelines for more information.
Total trihalomethanes (TTHMs) carcinogen
Exposure to elevated levels of this contaminant may pose health risks. See EWG and EPA guidelines for more information.
Bromochloroacetic acid
Exposure to elevated levels of this contaminant may pose health risks. See EWG and EPA guidelines for more information.
Dibromoacetic acid
Exposure to elevated levels of this contaminant may pose health risks. See EWG and EPA guidelines for more information.
Bromodichloromethane carcinogen
Bromodichloromethane is a trihalomethane (THM) disinfection byproduct that damages liver and kidneys with chronic exposure. EPA classifies it as a probable human carcinogen based on animal carcinogenicity data.
Recommended Filtration for This Water
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Shop Hydrogen FlaskFrequently Asked Questions
Is San Antonio tap water safe to drink?
San Antonio tap water meets EPA legal standards for drinking water. However, 15 contaminants exceed stricter EWG health guidelines, and 14 known carcinogens were detected. While legally compliant, additional filtration is recommended for optimal safety.
What contaminants are in San Antonio water?
A total of 38 contaminants were detected in San Antonio tap water, including Haloacetic acids (HAA9), Total trihalomethanes (TTHMs). Of these, 15 exceed EWG health guidelines.
What's the best water filter for San Antonio?
For San Antonio tap water, we recommend a reverse osmosis (RO) system for drinking water — it removes up to 99.9% of contaminants including heavy metals, PFAS, and disinfection byproducts. For shower and bath water, a whole-home filtration system reduces chlorine and volatile organics.
Where does San Antonio get its water?
San Antonio tap water is provided by San Antonio Water System, serving approximately 1,999,472 people. For detailed source water information, contact your local utility or visit the EPA's SDWIS database.
Nearby City Water Reports
Data sources: Environmental Working Group (EWG) Tap Water Database, U.S. EPA Safe Drinking Water Information System (SDWIS)
Last updated: March 2026
Methodology: Contaminant levels are compared against both EPA legal limits (Maximum Contaminant Levels) and EWG health guidelines, which are often stricter and based on the latest scientific research.
