Compliance record
Formal violations the EPA has on file for this supplier. A health-based violation means a contaminant limit or a required treatment was breached; the rest are monitoring or reporting failures — still violations, but not a measured health risk.
30
health-based violations
39
violations on file
0
still open
| Violation | Type | Status | Period |
|---|---|---|---|
| MCL | Health-based | Resolved | 2025-10-01 → 2025-12-31 |
| MCL | Health-based | Resolved | 2025-10-01 → 2025-12-31 |
| MCL | Health-based | Resolved | 2025-10-01 → 2025-12-31 |
| MCL | Health-based | Resolved | 2025-10-01 → 2025-12-31 |
| MCL | Health-based | Resolved | 2016-01-01 → 2016-03-31 |
| MCL | Health-based | Resolved | 2016-01-01 → 2016-03-31 |
| MCL | Health-based | Resolved | 2016-01-01 → 2016-03-31 |
| MCL | Health-based | Resolved | 2016-01-01 → 2016-03-31 |
| MCL | Health-based | Resolved | 2014-07-01 → 2014-09-30 |
| MCL | Health-based | Resolved | 2014-07-01 → 2014-09-30 |
PFAS detected
PFAS are industrial “forever chemicals”. These are the EPA's latest
nationwide test results (2023–2025).
Other contaminants detected
Each bar shows the measured level as a share of the EPA limit: green is
well under, amber is close to it, red is over. For lead and copper the
limit applies to exactly the 90th-percentile figure shown, so red there
means a real exceedance. For everything else the limit applies to a
running annual average while the figure is the 95th percentile of this
system's samples — over 100% is worth reading, but is not by itself a
violation. Where a single sample came in higher than that percentile, it
is noted under the bar. Formal violations are listed separately.
| Contaminant | Level vs EPA limit | Detection rate | Source | Period |
|---|---|---|---|---|
| Dibromochloromethane | 23.955 µg/L No EPA limit set
worst single sample: 33.7 µg/L | 282/288 | SYR4 | 2012–2019 |
| Bromoform | 8.6 µg/L No EPA limit set
worst single sample: 10.3 µg/L | 274/288 | SYR4 | 2012–2019 |
| Bromodichloromethane | 26.28 µg/L No EPA limit set
worst single sample: 33.9 µg/L | 272/288 | SYR4 | 2012–2019 |
| Chloroform | 27.585 µg/L No EPA limit set
worst single sample: 124 µg/L | 248/288 | SYR4 | 2012–2019 |
| TTHM | 88.075 µg/L 110% of the EPA limit, at the 95th percentile of samples — 80 µg/L
worst single sample: 158 µg/L | 246/251 | SYR4 | 2012–2019 |
| Total Haloacetic Acids (HAA5) | 35.025 µg/L 58% of the EPA limit 60 µg/L
worst single sample: 142 µg/L | 236/247 | SYR4 | 2012–2019 |
| Dibromoacetic Acid | 6.37 µg/L No EPA limit set
worst single sample: 8.9 µg/L | 234/247 | SYR4 | 2012–2019 |
| Dichloroacetic Acid | 16.95 µg/L No EPA limit set
worst single sample: 50.2 µg/L | 223/247 | SYR4 | 2012–2019 |
| Trichloroacetic Acid | 8.6 µg/L No EPA limit set
worst single sample: 86.5 µg/L | 206/247 | SYR4 | 2012–2019 |
| Copper | 250.5 µg/L 19% of the EPA limit 1300 µg/L
worst single sample: 740 µg/L | 200/210 | SYR4 | 2012–2018 |
| Nitrate | 1990.5 µg/L 20% of the EPA limit 10000 µg/L
worst single sample: 2580 µg/L | 114/114 | SYR4 | 2012–2019 |
| Lead | 4.2 µg/L 28% of the EPA limit 15 µg/L
worst single sample: 24 µg/L | 101/210 | SYR4 | 2012–2018 |
| Monobromoacetic Acid | 2.165 µg/L No EPA limit set
worst single sample: 4.1 µg/L | 50/247 | SYR4 | 2012–2019 |
| Monochloroacetic Acid | 12.32 µg/L No EPA limit set
worst single sample: 16.3 µg/L | 40/247 | SYR4 | 2012–2019 |
| Chlorite | 604 µg/L 60% of the EPA limit 1000 µg/L
worst single sample: 692 µg/L | 35/48 | SYR4 | 2017–2019 |
| Barium | 46.76 µg/L 2.3% of the EPA limit 2000 µg/L
worst single sample: 48.9 µg/L | 33/33 | SYR4 | 2013–2019 |
| Fluoride | 765 µg/L 19% of the EPA limit 4000 µg/L
worst single sample: 840 µg/L | 31/31 | SYR4 | 2012–2019 |
| Lead | 0.0016 mg/L 11% of the EPA limit 0.0150 mg/L | 14/14 | LCR | 2024 |
| Nitrate-Nitrite | 2172 µg/L 22% of the EPA limit 10000 µg/L
worst single sample: 2300 µg/L | 9/9 | SYR4 | 2012–2015 |
| Lithium | 11.3 µg/L No EPA limit set | 5/26 | UCMR-5 | 2024 |
| Combined Radium (-226 And -228) | 1.5 pCi/L 30% of the EPA limit 5 pCi/L | 4/4 | SYR4 | 2017 |
| Selenium | 4.1 µg/L 8.2% of the EPA limit 50 µg/L | 4/33 | SYR4 | 2013–2019 |
| Chromium | 1.9595 µg/L 2% of the EPA limit 100 µg/L
worst single sample: 1.97 µg/L | 2/33 | SYR4 | 2013–2019 |
| Antimony, Total | 0.2220 µg/L 3.7% of the EPA limit 6 µg/L | 1/33 | SYR4 | 2013–2019 |
| Arsenic | 2.2 µg/L 22% of the EPA limit 10 µg/L | 1/33 | SYR4 | 2013–2019 |
| Atrazine | 0.1600 µg/L 5.3% of the EPA limit 3 µg/L | 1/49 | SYR4 | 2012–2019 |
| Cyanide | 10 µg/L 5% of the EPA limit 200 µg/L | 1/26 | SYR4 | 2014–2019 |
| Di(2-ethylhexyl) Phthalate | 0.8700 µg/L 14% of the EPA limit 6 µg/L | 1/49 | SYR4 | 2012–2019 |
79 contaminants tested, none detected
1,1,1-Trichloroethane1,1,2-Trichloroethane1,1-Dichloroethylene1,2,4-Trichlorobenzene1,2-DIBROMO-3-CHLOROPROPANE1,2-Dichloroethane1,2-Dichloropropane11Cl-PF3OUdS2,4,5-TP2,4-D4:2 Fts6:2 Fts8:2 Fts9Cl-PF3ONSAdonaAsbestosBhc-GammaBenzeneBenzo(A)PyreneBeryllium, TotalChlorobenzeneCadmiumCarbofuranCarbon TetrachlorideChlordaneCombined UraniumDichloromethaneDalaponDi(2-ethylhexyl) AdipateDinosebEthylene DibromideEndrinEthylbenzeneGross Alpha, Excl. Radon And UGross Beta Particle ActivityHexachlorobenzeneHfpo-DaHeptachlorHeptachlor EpoxideHexachlorocyclopentadieneLassoMercuryMethoxychlorNetfosaaNfdhaNmefosaaNitriteOxamylPFBSPfdaPfdoaPfeesaPfhpaPfhpsPfhxaPfmbaPfmpaPFNAPFOAPFOSPfpesPftaPftrdaPfunaPentachlorophenolPicloramSimazineStyreneTetrachloroethyleneThallium, TotalTolueneToxapheneTrichloroethyleneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene
Utility contact
Frequently asked questions about City of San Marcos
Is City of San Marcos tap water safe to drink?
EPA monitoring detected 31 contaminants in City of San Marcos's water. A detection isn't the same as a violation — most levels are within federal limits. See each level and source above, and the utility's annual Consumer Confidence Report for its official compliance status.
What contaminants were detected in City of San Marcos's water?
EPA monitoring detected Dibromochloromethane, Bromoform, Bromodichloromethane, Chloroform, TTHM, and others. The full list with the level and data source for each is above.
How many people does City of San Marcos serve?
City of San Marcos reports serving 72,970 people in Texas, per its EPA record.
Has City of San Marcos had any water quality violations?
The EPA has 39 violations on file for City of San Marcos, of which 30 are health-based (a contaminant limit or required treatment was breached) and 0 remain open. The rest are monitoring or reporting failures.
Where does this data come from?
Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.