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.
21
health-based violations
24
violations on file
0
still open
| Violation | Type | Status | Period |
|---|---|---|---|
| MCL | Health-based | Resolved | 2013-08-01 → 2013-08-31 |
| MCL | Health-based | Resolved | 2013-08-01 → 2013-08-31 |
| MCL | Health-based | Resolved | 2007-03-01 → 2007-03-31 |
| MCL | Health-based | Resolved | 2007-03-01 → 2007-03-31 |
| MCL | Health-based | Resolved | 1996-02-01 → 1996-02-29 |
| MCL | Health-based | Resolved | 1996-02-01 → 1996-02-29 |
| MCL | Health-based | Resolved | 1995-09-01 → 1995-09-30 |
| MCL | Health-based | Resolved | 1995-09-01 → 1995-09-30 |
| MCL | Health-based | Resolved | 1995-05-01 → 1995-05-31 |
| MCL | Health-based | Resolved | 1995-05-01 → 1995-05-31 |
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 |
|---|---|---|---|---|
| Nitrate | 8382.07 µg/L 84% of the EPA limit 10000 µg/L
worst single sample: 21000 µg/L | 12032/12254 | SYR4 | 2012–2019 |
| Nitrate-Nitrite | 8435 µg/L 84% of the EPA limit 10000 µg/L
worst single sample: 16000 µg/L | 5231/5297 | SYR4 | 2012–2018 |
| Combined Uranium | 34.27 µg/L 114% of the EPA limit, at the 95th percentile of samples — 30 µg/L
worst single sample: 71.52 µg/L | 2492/2649 | SYR4 | 2012–2019 |
| Arsenic | 7.4 µg/L 74% of the EPA limit 10 µg/L
worst single sample: 12 µg/L | 630/1638 | SYR4 | 2012–2019 |
| 1,2-DIBROMO-3-CHLOROPROPANE | 0.3925 µg/L 196% of the EPA limit, at the 95th percentile of samples — 0.2000 µg/L
worst single sample: 0.7000 µg/L | 576/1233 | SYR4 | 2012–2019 |
| TTHM | 74.3525 µg/L 93% of the EPA limit 80 µg/L
worst single sample: 98.16 µg/L | 276/449 | SYR4 | 2012–2019 |
| Chloroform | 71.0875 µg/L No EPA limit set
worst single sample: 94.45 µg/L | 252/450 | SYR4 | 2012–2019 |
| Trichloroethylene | 24.1 µg/L 482% of the EPA limit, at the 95th percentile of samples — 5 µg/L
worst single sample: 54 µg/L | 239/573 | SYR4 | 2012–2019 |
| Total Haloacetic Acids (HAA5) | 43.325 µg/L 72% of the EPA limit 60 µg/L
worst single sample: 61.1 µg/L | 236/249 | SYR4 | 2012–2019 |
| Dichloroacetic Acid | 23.86 µg/L No EPA limit set
worst single sample: 32.9 µg/L | 232/247 | SYR4 | 2012–2019 |
| Trichloroacetic Acid | 22.27 µg/L No EPA limit set
worst single sample: 32.2 µg/L | 232/247 | SYR4 | 2012–2019 |
| Bromodichloromethane | 5.57 µg/L No EPA limit set
worst single sample: 13.8 µg/L | 224/463 | SYR4 | 2012–2019 |
| Nitrite | 0.1200 µg/L 0% of the EPA limit 1000 µg/L
worst single sample: 0.9500 µg/L | 170/5319 | SYR4 | 2012–2019 |
| Tetrachloroethylene | 15 µg/L 300% of the EPA limit, at the 95th percentile of samples — 5 µg/L
worst single sample: 22 µg/L | 121/573 | SYR4 | 2012–2019 |
| Dibromochloromethane | 4.7525 µg/L No EPA limit set
worst single sample: 9.92 µg/L | 120/405 | SYR4 | 2012–2019 |
| Barium | 240 µg/L 12% of the EPA limit 2000 µg/L
worst single sample: 310 µg/L | 97/177 | SYR4 | 2012–2019 |
| Bromoform | 3.9155 µg/L No EPA limit set
worst single sample: 6.67 µg/L | 78/392 | SYR4 | 2012–2019 |
| Fluoride | 175 µg/L 4.4% of the EPA limit 4000 µg/L
worst single sample: 1200 µg/L | 59/177 | SYR4 | 2012–2019 |
| Dibromoacetic Acid | 2.34 µg/L No EPA limit set
worst single sample: 2.9 µg/L | 33/162 | SYR4 | 2012–2019 |
| Lead | 0.0120 mg/L 80% of the EPA limit 0.0150 mg/L | 31/31 | LCR | 2027 |
| Monochloroacetic Acid | 4.92 µg/L No EPA limit set
worst single sample: 5.3 µg/L | 23/167 | SYR4 | 2012–2019 |
| Lithium | 21 µg/L No EPA limit set | 13/86 | UCMR-5 | 2024 |
| 1,1-Dichloroethylene | 0.7300 µg/L 10% of the EPA limit 7 µg/L
worst single sample: 0.9900 µg/L | 11/572 | SYR4 | 2012–2019 |
| Selenium | 6.12 µg/L 12% of the EPA limit 50 µg/L
worst single sample: 6.2 µg/L | 3/177 | SYR4 | 2012–2019 |
| Combined Radium (-226 And -228) | 1.183 pCi/L 24% of the EPA limit 5 pCi/L
worst single sample: 1.19 pCi/L | 2/2 | SYR4 | 2013–2015 |
| Gross Beta Particle Activity | 3.557 pCi/L No EPA limit set
worst single sample: 3.67 pCi/L | 2/2 | SYR4 | 2015–2017 |
| Chromium | 6.4 µg/L 6.4% of the EPA limit 100 µg/L | 1/177 | SYR4 | 2012–2019 |
| Monobromoacetic Acid | 2 µg/L No EPA limit set | 1/158 | SYR4 | 2012–2019 |
79 contaminants tested, none detected
1,1,1-Trichloroethane1,1,2-Trichloroethane1,2,4-Trichlorobenzene1,2-Dichloroethane1,2-Dichloropropane11Cl-PF3OUdS2,3,7,8-TCDD2,4,5-TP2,4-D4:2 Fts6:2 Fts8:2 Fts9Cl-PF3ONSAdonaAntimony, TotalAsbestosAtrazineBhc-GammaBenzeneBenzo(A)PyreneBeryllium, TotalChlorobenzeneCopperCyanideCadmiumCarbofuranCarbon TetrachlorideChlordaneChloriteDichloromethaneDalaponDi(2-ethylhexyl) AdipateDi(2-ethylhexyl) PhthalateDinosebDiquatEthylene DibromideEndothallEndrinEthylbenzeneGlyphosateHexachlorobenzeneHfpo-DaHeptachlorHeptachlor EpoxideHexachlorocyclopentadieneLassoLeadMercuryMethoxychlorNetfosaaNfdhaNmefosaaOxamylPfbaPfdaPfdoaPfeesaPfhpsPfmbaPfmpaPFNAPfpesPftaPftrdaPfunaPentachlorophenolPicloramSimazineStyreneThallium, TotalTolueneTotal Polychlorinated Biphenyls (PCB)ToxapheneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene
Utility contact
Frequently asked questions about Modesto, City of
Is Modesto, City of tap water safe to drink?
EPA monitoring detected 35 contaminants in Modesto, City of'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 Modesto, City of's water?
EPA monitoring detected Nitrate, Nitrate-Nitrite, Combined Uranium, Arsenic, 1,2-DIBROMO-3-CHLOROPROPANE, and others. The full list with the level and data source for each is above.
How many people does Modesto, City of serve?
Modesto, City of reports serving 218,771 people in California, per its EPA record.
Has Modesto, City of had any water quality violations?
The EPA has 24 violations on file for Modesto, City of, of which 21 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.