Tap water · TX
San Antonio Water System
EPA system ID TX0150018 · serves about 2,643,729 people. Every US utility must publish an annual water quality report — here’s the official one (2025), and below it, our plain-English translation.
Read the official report →What San Antonio Water System found in 2025
26 detected analytes from the utility’s own annual report, hand-normalized — 1 was near or over a limit (flagged below).
| Detected | Level | Limit | % of limit | Status |
|---|---|---|---|---|
| Total Trihalomethanes (TTHMs) | 86.2 ppb | 80 ppb | 108% | Over limit† |
| Chlorine Residual, Free | 2.32 ppm | 4 ppm | 58% | Within limit |
| Haloacetic Acids (HAA5) | 30.6 ppb | 60 ppb | 51% | Within limit |
| Thallium, Total | 0.61 ppb | 2 ppb | 31% | Within limit |
| Combined Radium 226/228 | 1.5 pCi/L | 5 pCi/L | 30% | Within limit |
| Gross Alpha Excluding Radon and Uranium | 3.9 pCi/L | 15 pCi/L | 26% | Within limit |
| Nitrate [measured as Nitrogen] | 2.45 ppm | 10 ppm | 25% | Within limit |
| Alpha Emitters | 3 pCi/L | 15 pCi/L | 20% | Within limit |
| Radium 228 | 1 pCi/L | 5 pCi/L | 20% | Within limit |
| Nitrate-Nitrite | 1.83 ppm | 10 ppm | 18% | Within limit |
| Fluoride | 0.69 ppm | 4 ppm | 17% | Within limit |
| Copper (90th percentile) | 0.187 ppm | 1.3 ppm | 14% | Within limit |
| Fluoride (highest printed 0) | 0.5 ppb | 4 ppb | 13% | Within limit |
| Beta/photon Emitters | 5.5 pCi/L | 50 pCi/L | 11% | Within limit |
| Lead (90th percentile) | 1.6 ppb | 15 ppb | 11% | Within limit |
| Barium | 0.125 ppm | 2 ppm | 6% | Within limit |
| Selenium | 3.1 ppb | 50 ppb | 6% | Within limit |
| Uranium | 1.7 µg/L | 30 µg/L | 6% | Within limit |
| Nitrate | 0.06 ppm | 10 ppm | 1% | Within limit |
| Diethylhexyl Adipate | 1 ppb | 400 ppb | 0% | Within limit |
| Xylenes, Total | 0.001 ppm | 10 ppm | 0% | Within limit |
| Lithium | 15.6 ppb | — | — | No federal limit |
| Dibromochloromethane | 9.9 ppb | — | — | No federal limit |
| Coliform Bacteria | 0.17 | — | — | No federal limit |
| Turbidity (highest) | 0.09 NTU | — | — | No federal limit |
| Nickel | 0.004 ppm | — | — | No federal limit |
† Above the printed limit at one or more sampling locations, but the utility reports no violation — regulatory compliance for this analyte is calculated differently (e.g. system-wide or running annual averages). The linked official report has the details.
Levels and limits are as printed in the utility’s report (“limit” is the EPA MCL, action level, residual limit, or secondary guideline that applies to that row; “ND” = not detected). Utilities publish these reports annually — we re-check every covered utility each July, after the federal publication deadline. Detected doesn’t mean dangerous — most detections sit far below their limits. This is education, not medical advice.
Zip codes covered
78201 · 78202 · 78203 · 78204 · 78205 · 78207 · 78208 · 78210 · 78211 · 78212 · 78213 · 78214 · 78215 · 78216 · 78217 · 78218 · 78220 · 78221 · 78222 · 78223 · 78224 · 78225 · 78226 · 78227 · 78228 · 78229 · 78230 · 78232 · 78235 · 78237 · 78240 · 78242 · 78244 · 78245 · 78247 · 78248 · 78249 · 78250 · 78251 · 78253 · 78254 · 78255 · 78256 · 78257 · 78258 · 78259 · 78260 · 78261
Boundary zips partially served by other systems are deliberately unlisted — check your exact zip.