- EPA's UCMR 5 testing looked for 30 contaminants here and found 3.
- Lithium: found in 11 of 12 samples, average 17.6 µg/L, highest 25 µg/L (EPA UCMR 5 testing, May 2023–Feb 2024)
- PFPeA (a PFAS): found in 2 of 12 samples, average 0.60 ppt, highest 4.7 ppt (EPA UCMR 5 testing, May 2023–Feb 2024)
- PFBA (a PFAS): found in 1 of 12 samples, average 0.40 ppt, highest 5.1 ppt (EPA UCMR 5 testing, May 2023–Feb 2024)
- Lead: 9 in 10 homes tested came in at or below 2 ppb, at or below EPA's 15 ppb action level (latest EPA result for a testing period that ran on or after July 1, 2021: Jan 1, 2026–Jun 30, 2026). This is one number for the whole water system, from homes the utility tested. It isn't a result for your home.
Public EPA test results
Can you drink Castle Rock tap water? What EPA records show
EPA system ID CO0118010 · serves Douglas County, CO · about 110,298 people (EPA records)
Here's what EPA has on file for this water system: its testing for newer contaminants like PFAS (UCMR 5), lead testing and violations. It's not a test of your tap, and there's no Water Score here.
Public EPA test results
Castle Rock Town of (EPA CO0118010)
EPA data as of October 14, 2026. For Castle Rock's main utility, Castle Rock Town of: We found no health-standard violations in EPA's records for this system (CO0118010) since July 1, 2021, as of October 14, 2026. PFOA and PFOS were not detected at or above EPA's reporting level in EPA's UCMR 5 testing.
What EPA records show for Castle Rock Town of, as of October 14, 2026
We found no health-standard violations in EPA's records for this system (CO0118010) since July 1, 2021, as of October 14, 2026.
Source: EPA ECHO record for Castle Rock Town of (SDWIS). Data as of October 14, 2026.
Lead: 9 in 10 homes tested came in at or below 2 ppb, at or below EPA's 15 ppb action level (latest EPA result for a testing period that ran on or after July 1, 2021: Jan 1, 2026–Jun 30, 2026). This is one number for the whole water system, from homes the utility tested. It isn't a result for your home.
EPA's UCMR 5 testing looked for 30 contaminants here and found 3.
PFOA and PFOS were not detected at or above EPA's reporting level in EPA's UCMR 5 testing.
Source: EPA records (SDWIS, UCMR 5). SDWIS: data as of Oct 14, 2026. EPA UCMR 5 data, samples through June 2026.
Your water bill names your utility.
Does Castle Rock Town of use chloramine?
EPA treatment records (state-reported) list chloramines for Castle Rock Town of. EPA record