June 14, 2026
Castle Rock, CO Water Quality Report 2026
Unlock the full breakdown — detected levels vs. legal limits, plus what removes each one.
Full contaminant breakdown
EPA Six-Year Review compliance monitoring, 2012–2019 — the most recent national compliance dataset EPA has published. See the sections above for more recent violation and PFAS records.
| Contaminant | Avg. detected | Highest sample | Federal limit | Avg. vs. limit |
|---|---|---|---|---|
| Thallium | 2 ppb | 2 ppb | 2 ppb | 100% |
| Radium (combined)EPA health goal: zero | 2.79 pCi/L | 5.2 pCi/L | 5 pCi/L | 56% |
| DEHP (phthalate)EPA health goal: zero | 1.9 ppb | 1.9 ppb | 6 ppb | 32% |
| Gross alpha radioactivityEPA health goal: zero | 3.61 pCi/L | 7.63 pCi/L | 15 pCi/L | 24% |
| Fluoride | 793 ppb | 1100 ppb | 4000 ppb | 20% |
| ArsenicEPA health goal: zero | 1.9 ppb | 1.9 ppb | 10 ppb | 19% |
| Barium | 156 ppb | 520 ppb | 2000 ppb | 8% |
| Total trihalomethanes (TTHMs) | 5.2 ppb | 67.5 ppb | 80 ppb | 6% |
| UraniumEPA health goal: zero | 1.44 ppb | 3 ppb | 30 ppb | 5% |
| Selenium | 2.55 ppb | 5 ppb | 50 ppb | 5% |
| Haloacetic acids (HAA5) | 2.7 ppb | 9.3 ppb | 60 ppb | 4% |
| Chromium (total) | 1.86 ppb | 3 ppb | 100 ppb | 2% |
| Nitrate | 180 ppb | 350 ppb | 10000 ppb | 2% |
| Nitrate + nitrite | 211 ppb | 350 ppb | 10000 ppb | 2% |
| Ethylbenzene | 2.3 ppb | 2.3 ppb | 700 ppb | <1% |
| Picloram | 0.1 ppb | 0.1 ppb | 500 ppb | <1% |
| Xylenes (total) | 15.7 ppb | 27.5 ppb | 10000 ppb | <1% |
Also tested, no detections: 1,1,1-Trichloroethane, 1,1,2-Trichloroethane, 1,1-Dichloroethylene, 1,2,4-Trichlorobenzene, 1,2-Dichloroethane, 1,2-Dichloropropane, 2,4,5-TP (Silvex), 2,4-D, Alachlor, Antimony, Atrazine, Benzene, Benzo(a)pyrene, Beryllium, Cadmium, Carbofuran, Carbon tetrachloride, Chlordane, Chlorobenzene, Cyanide, DBCP, DEHA (adipate), Dalapon, Dichloromethane, Dinoseb, Dioxin (2,3,7,8-TCDD), Diquat, Endothall, Endrin, Ethylene dibromide (EDB), Glyphosate, Heptachlor, Heptachlor epoxide, Hexachlorobenzene, Hexachlorocyclopentadiene, Lindane, Mercury (inorganic), Methoxychlor, Nitrite, Oxamyl, PCBs, Pentachlorophenol, Simazine, Styrene, Tetrachloroethylene (PCE), Toluene, Toxaphene, Trichloroethylene (TCE), Vinyl chloride, cis-1,2-Dichloroethylene, o-Dichlorobenzene, p-Dichlorobenzene, trans-1,2-Dichloroethylene.
Reverse osmosis (drinking water)
The treatment category most often matched to dissolved contaminants like lead, arsenic, nitrate, fluoride, and radiological contaminants detected in this system.
Shop reverse osmosis →Whole-house carbon filtration
The treatment category most often matched to disinfection byproducts (TTHMs, haloacetic acids), chlorine taste and odor, and organic compounds detected in this system.
Shop whole-house systems →Source: U.S. EPA Six-Year Review 4 compliance monitoring data (2012–2019), the most recent nationwide compliance dataset EPA has released, reported at the water-system level. A detection is not a violation. “Avg. vs. limit” compares the average of laboratory detections to the federal MCL or action level; individual faucets can differ — household plumbing affects lead and copper, and a state-certified laboratory test of your own tap is the only way to confirm levels in your home. Treatment categories are general matches, not a certification claim for a specific product and contaminant.
Water Utility: Castle Rock Town Of
Population Served: 106,822 residents
Data Sources: EPA SDWIS + EPA UCMR5
Report Year: 2026
Castle Rock, Colorado drinking water is supplied by Castle Rock Town Of. All US public water systems must test drinking water and report results to the EPA under the Safe Drinking Water Act. This report summarizes health-based violations and PFAS detections recorded in federal databases to help you make informed decisions about home water filtration.
EPA Violation History
No health-based EPA maximum contaminant level (MCL) violations on record since 2010 for this utility.
PFAS "Forever Chemical" Detections
PFAS compounds were detected in this water system during EPA's Fifth Unregulated Contaminant Monitoring Rule (UCMR5) testing program (2023-2025). EPA has set maximum contaminant levels of 4 parts per trillion (ppt) for PFOA and PFOS individually.
| PFAS Compound | Level Detected | Solution |
|---|---|---|
| PFBA | 0.0051 ug/L | PFAS Filters |
| PFPeA | 0.0047 ug/L | PFAS Filters |
Source: EPA UCMR5 occurrence data. Levels in micrograms per liter (ug/L = parts per billion). 1 ug/L = 1,000 ppt.
Should You Filter Your Castle Rock Water?
Even utilities with no EPA violations may have contaminants present below legal limits but above health guidelines. The EPA sets maximum contaminant levels based on what is feasible and affordable to treat at scale -- not necessarily what carries zero health risk. Many independent health organizations recommend filtration for households with children, pregnant women, or immunocompromised individuals regardless of utility compliance status.
Protect Your Castle Rock Home Water
PureWaterGuys.com carries filtration systems engineered to address the most common contaminants in US tap water. We ship to all Colorado addresses with free expert guidance on the right system.
Shop Water Filtration Systems →Take the Water QuizFrequently Asked Questions
Is Castle Rock tap water safe to drink?
Castle Rock Town Of is required to meet EPA federal drinking water standards. However, meeting legal standards is not the same as being contaminant-free. Trace levels of disinfection byproducts, PFAS compounds, and other regulated contaminants are common in US municipal water systems.
Does Castle Rock water have PFAS?
PFAS compounds were detected in this utility's water during EPA UCMR5 monitoring. A certified PFAS filter -- such as reverse osmosis or activated carbon block -- can significantly reduce these compounds at your tap.
What water filter works best for Castle Rock?
A whole-house carbon block filter removes chlorine, chloramines, and many VOCs. For PFAS, arsenic, and nitrates, a reverse osmosis under-sink system provides the highest reduction rates. Take our free 2-minute quiz to find the right system for your home and budget.
Data sourced from EPA SDWIS and UCMR5 federal databases. PureWaterGuys.com is not affiliated with any municipal water utility. Contact your utility's annual Consumer Confidence Report (CCR) for complete local data.