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.
0
health-based violations
36
violations on file
0
still open
| Violation | Type | Status | Period |
|---|---|---|---|
| MR | Monitoring | Resolved | 2023-11-01 → 2023-11-30 |
| MR | Monitoring | Resolved | 2023-11-01 → 2023-11-30 |
| MR | Monitoring | Resolved | 2023-11-01 → 2023-11-30 |
| MR | Monitoring | Resolved | 2023-11-01 → 2023-11-30 |
| MR | Monitoring | Resolved | 2023-10-01 → 2023-10-31 |
| MR | Monitoring | Resolved | 2023-10-01 → 2023-10-31 |
| MR | Monitoring | Resolved | 2023-10-01 → 2023-10-31 |
| MR | Monitoring | Resolved | 2023-10-01 → 2023-10-31 |
| MR | Monitoring | Resolved | 2023-09-01 → 2023-09-30 |
| MR | Monitoring | Resolved | 2023-09-01 → 2023-09-30 |
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 |
|---|---|---|---|---|
| TTHM | 56.55 µg/L 71% of the EPA limit 80 µg/L
worst single sample: 78.14 µg/L | 766/766 | SYR4 | 2012–2019 |
| Total Haloacetic Acids (HAA5) | 28.97 µg/L 48% of the EPA limit 60 µg/L
worst single sample: 44 µg/L | 763/765 | SYR4 | 2012–2019 |
| Bromodichloromethane | 20.33 µg/L No EPA limit set
worst single sample: 25.4 µg/L | 100/100 | SYR4 | 2012–2019 |
| Chloroform | 25 µg/L No EPA limit set
worst single sample: 27 µg/L | 100/100 | SYR4 | 2012–2019 |
| Dibromochloromethane | 15.55 µg/L No EPA limit set
worst single sample: 18.8 µg/L | 100/100 | SYR4 | 2012–2019 |
| Bromoform | 7.215 µg/L No EPA limit set
worst single sample: 7.5 µg/L | 98/100 | SYR4 | 2012–2019 |
| Dibromoacetic Acid | 5.075 µg/L No EPA limit set
worst single sample: 5.64 µg/L | 96/96 | SYR4 | 2016–2019 |
| Dichloroacetic Acid | 12 µg/L No EPA limit set
worst single sample: 16.1 µg/L | 96/96 | SYR4 | 2016–2019 |
| Trichloroacetic Acid | 8.235 µg/L No EPA limit set
worst single sample: 10 µg/L | 96/96 | SYR4 | 2016–2019 |
| Nitrate | 930.5 µg/L 9.3% of the EPA limit 10000 µg/L
worst single sample: 1160 µg/L | 30/32 | SYR4 | 2012–2019 |
| Lead | 0.0023 mg/L 15% of the EPA limit 0.0150 mg/L | 27/27 | LCR | 2025 |
| Barium | 49.525 µg/L 2.5% of the EPA limit 2000 µg/L
worst single sample: 52.5 µg/L | 18/18 | SYR4 | 2012–2019 |
| Bromate | 1.44 µg/L 14% of the EPA limit 10 µg/L
worst single sample: 1.6 µg/L | 17/76 | SYR4 | 2012–2019 |
| Fluoride | 902.5 µg/L 23% of the EPA limit 4000 µg/L
worst single sample: 910 µg/L | 16/16 | SYR4 | 2012–2019 |
| Nitrate-Nitrite | 870 µg/L 8.7% of the EPA limit 10000 µg/L
worst single sample: 1200 µg/L | 13/14 | SYR4 | 2013–2019 |
| Combined Uranium | 6.047 µg/L 20% of the EPA limit 30 µg/L
worst single sample: 7.4 µg/L | 12/14 | SYR4 | 2012–2018 |
| Chromium | 1.66 µg/L 1.7% of the EPA limit 100 µg/L
worst single sample: 1.8 µg/L | 8/18 | SYR4 | 2012–2019 |
| Gross Alpha, Excl. Radon And U | 2.64 pCi/L 18% of the EPA limit 15 pCi/L
worst single sample: 2.7 pCi/L | 7/13 | SYR4 | 2012–2018 |
| Lithium | 34 µg/L No EPA limit set | 7/7 | UCMR-5 | 2023 |
| Monobromoacetic Acid | 1.0975 µg/L No EPA limit set
worst single sample: 1.1 µg/L | 6/96 | SYR4 | 2016–2019 |
| Gross Beta Particle Activity | 5.856 pCi/L No EPA limit set
worst single sample: 5.86 pCi/L | 5/7 | SYR4 | 2014–2017 |
| Combined Radium (-226 And -228) | 0.8105 pCi/L 16% of the EPA limit 5 pCi/L
worst single sample: 0.8300 pCi/L | 4/13 | SYR4 | 2012–2018 |
| Nitrite | 591 µg/L 59% of the EPA limit 1000 µg/L
worst single sample: 650 µg/L | 3/14 | SYR4 | 2013–2019 |
| Antimony, Total | 0.2655 µg/L 4.4% of the EPA limit 6 µg/L
worst single sample: 0.2700 µg/L | 2/18 | SYR4 | 2012–2019 |
| Arsenic | 0.8990 µg/L 9% of the EPA limit 10 µg/L
worst single sample: 0.9300 µg/L | 2/18 | SYR4 | 2012–2019 |
80 contaminants tested, none detected
1,1,1-Trichloroethane1,1,2-Trichloroethane1,1-Dichloroethylene1,2,4-Trichlorobenzene1,2-DIBROMO-3-CHLOROPROPANE1,2-Dichloroethane1,2-Dichloropropane11Cl-PF3OUdS2,3,7,8-TCDD2,4,5-TP2,4-D4:2 Fts6:2 Fts8:2 Fts9Cl-PF3ONSAdonaAtrazineBhc-GammaBenzeneBenzo(A)PyreneBeryllium, TotalChlorobenzeneCopperCyanideCadmiumCarbofuranCarbon TetrachlorideChlordaneDichloromethaneDalaponDi(2-ethylhexyl) AdipateDi(2-ethylhexyl) PhthalateDinosebDiquatEthylene DibromideEndothallEndrinEthylbenzeneGlyphosateHexachlorobenzeneHfpo-DaHeptachlorHeptachlor EpoxideHexachlorocyclopentadieneLassoMercuryMethoxychlorMonochloroacetic AcidNetfosaaNfdhaNmefosaaOxamylPfdaPfdoaPfeesaPfhpsPfmbaPfmpaPFNAPfpesPftaPftrdaPfunaPentachlorophenolPicloramSeleniumSimazineStyreneTetrachloroethyleneThallium, TotalTolueneTotal Polychlorinated Biphenyls (PCB)ToxapheneTrichloroethyleneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene
Utility contact
Frequently asked questions about Thornton City of
Is Thornton City of tap water safe to drink?
EPA monitoring detected 33 contaminants in Thornton 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 Thornton City of's water?
EPA monitoring detected TTHM, Total Haloacetic Acids (HAA5), Bromodichloromethane, Chloroform, Dibromochloromethane, and others. The full list with the level and data source for each is above.
How many people does Thornton City of serve?
Thornton City of reports serving 226,465 people in Colorado, per its EPA record.
Has Thornton City of had any water quality violations?
The EPA has 36 violations on file for Thornton City of, of which 0 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.