CO / Thornton
CO · Tap water records
Thornton tap water, in plain English
Here is what the EPA's own data shows about tap water in Thornton. According to EPA SDWIS data retrieved June 2026, Thornton is served by 5 active community water systems, together reported to serve about 230,581 people.
As of June 2026, EPA records show 303 violations across the community water system(s) serving Thornton, going back to the earliest EPA record. 5 of these are classified by the EPA as health-based (a contaminant recorded above the limit the EPA tracks); the rest are monitoring or reporting violations. Each is listed by system below, with its status.
What the EPA has on record, by system
Thornton City Of
226,465 served · surface water · PWSID CO0101150 - Monitoring Interim Enhanced Surface Water Treatment Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 13 times between May 2021 and November 2023. All have since returned to compliance, per EPA records.
- Monitoring Lead and Copper Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 4 times in July 2023. All have since returned to compliance, per EPA records.
- Monitoring Combined Radium (-226 and -228): a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in April 2022. All have since returned to compliance, per EPA records.
- Monitoring Combined Uranium: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in April 2022. All have since returned to compliance, per EPA records.
- Monitoring Gross Alpha, Excl. Radon and U: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in April 2022. All have since returned to compliance, per EPA records.
Woodland Hills Mhc
1,740 served · surface water · PWSID CO0101833 - Monitoring Surface Water Treatment Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 4 times in April 2022. All have since returned to compliance, per EPA records.
- Monitoring Chloramine: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in April 2022. All have since returned to compliance, per EPA records.
The Grove At Alta Ridge
1,300 served · surface water · PWSID CO0101320 - Health-based Stage 1 Disinfectants and Disinfection Byproducts Rule: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 2 times in August 2022. The EPA record for these does not include a measured level. All have since returned to compliance, per EPA records.
- Monitoring Revised Total Coliform Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 10 times between June 2022 and October 2022. All have since returned to compliance, per EPA records.
- Monitoring Stage 2 Disinfectants and Disinfection Byproducts Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 4 times in October 2022. All have since returned to compliance, per EPA records.
- Monitoring Public Notice: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 2 times in September 2022. All have since returned to compliance, per EPA records.
- Monitoring Surface Water Treatment Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 12 times between June 2022 and September 2022. All have since returned to compliance, per EPA records.
- Monitoring TTHM: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2022. All have since returned to compliance, per EPA records.
- Monitoring Total Haloacetic Acids (HAA5): a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2022. All have since returned to compliance, per EPA records.
- Monitoring Chloramine: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 6 times between April 2022 and July 2022. All have since returned to compliance, per EPA records.
Friendly Village Of The Rockies
1,046 served · surface water · PWSID CO0101283 - Monitoring Public Notice: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in December 2025. EPA records do not show all of these as returned to compliance.
- Monitoring Consumer Confidence Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in July 2025. EPA records do not show all of these as returned to compliance.
- Monitoring Lead and Copper Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 4 times between January 2023 and January 2025. All have since returned to compliance, per EPA records.
G And M Mobile Home Park
30 served · groundwater · PWSID CO0153300 - Health-based Stage 1 Disinfectants and Disinfection Byproducts Rule: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 3 times in September 2024. The EPA record for these does not include a measured level. All have since returned to compliance, per EPA records.
- Monitoring Public Notice: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 7 times between October 2024 and July 2025. All have since returned to compliance, per EPA records.
- Monitoring Gross Alpha, Excl. Radon and U: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 5 times between July 2024 and July 2025. EPA records do not show all of these as returned to compliance.
- Monitoring Combined Uranium: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 6 times between July 2024 and July 2025. EPA records do not show all of these as returned to compliance.
- Monitoring Combined Radium (-226 and -228): a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 5 times between July 2024 and July 2025. EPA records do not show all of these as returned to compliance.
- Monitoring Revised Total Coliform Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 7 times between July 2024 and March 2025. All have since returned to compliance, per EPA records.
- Monitoring Lead and Copper Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in March 2025. All have since returned to compliance, per EPA records.
- Monitoring TTHM: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in January 2025. EPA records do not show all of these as returned to compliance.
- Monitoring Total Haloacetic Acids (HAA5): a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in January 2025. EPA records do not show all of these as returned to compliance.
- Monitoring Barium: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Cadmium: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Chromium: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Mercury: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Nickel: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Sodium: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Antimony, Total: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Beryllium, Total: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Thallium, Total: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Selenium: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Endrin: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring BHC-GAMMA: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Methoxychlor: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Toxaphene: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Dalapon: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Diquat: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Endothall: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Di(2-ethylhexyl) adipate: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring OXAMYL: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Simazine: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Di(2-ethylhexyl) phthalate: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Picloram: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Dinoseb: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Hexachlorocyclopentadiene: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Carbofuran: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Atrazine: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring LASSO: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Heptachlor: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Heptachlor epoxide: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring 2,4-D: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Nitrate: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring 2,4,5-TP: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring HEXACHLOROBENZENE: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Benzo(a)pyrene: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Pentachlorophenol: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Total Polychlorinated Biphenyls (PCB): a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring 1,2-DIBROMO-3-CHLOROPROPANE: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring ETHYLENE DIBROMIDE: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Chlordane: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring 1,2,4-Trichlorobenzene: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring cis-1,2-Dichloroethylene: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Fluoride: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Xylenes, Total: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring DICHLOROMETHANE: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring o-Dichlorobenzene: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring p-Dichlorobenzene: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Vinyl chloride: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring 1,1-Dichloroethylene: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring trans-1,2-Dichloroethylene: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring 1,2-Dichloroethane: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring 1,1,1-Trichloroethane: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Carbon tetrachloride: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring 1,2-Dichloropropane: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Trichloroethylene: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring 1,1,2-Trichloroethane: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Tetrachloroethylene: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring CHLOROBENZENE: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Benzene: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Toluene: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Ethylbenzene: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Styrene: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Arsenic: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 3 times in July 2024. EPA records do not show all of these as returned to compliance.
What this means
A health-based violation means a contaminant was recorded above the limit the EPA tracks for it. A monitoring or reporting violation means a required test or report was late or missed — not that a contaminant was measured above a limit. “Returned to compliance” means the EPA recorded the issue as resolved.
This page summarizes the EPA's own records and does not assess whether your water is safe to drink. For the most current details, you can verify every record directly with the EPA, and contact your water system with questions.
Source: U.S. EPA Envirofacts SDWIS, retrieved June 2026. Records cover the EPA's full reporting history for these systems. Verify at EPA ECHO.