Castle Rock Town Of, CO
Lead detected, under the action levels
Latest 90th-percentile lead: 2 ppb (monitoring period 2026-2026). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. Lead was measured in sampled homes but the 90th percentile is under both action levels. EPA's health goal for lead is zero, so test your own tap if your home was built before 1986 or anyone in it is pregnant or a young child.
Castle Rock Town Of at a glance
Castle Rock Town Of serves about 110,298 people through 27,865 service connections, which makes it a very large system under EPA's size classes. It is owned by a local government (city, town, county or district) and draws surface water, in Douglas County, Colorado. EPA system ID: CO0118010; phone on file: 720-733-6041. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Lead results over time
Against the period ending 2025 (2 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Castle Rock Town Of is 4 ppb across 20 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2026 | 2 ppb |
| 2025 | 2 ppb |
| 2025 | 2 ppb |
| 2024 | 2 ppb |
| 2024 | 2 ppb |
| 2023 | 2 ppb |
| 2023 | 2 ppb |
| 2022 | 3 ppb |
| 2022 | 2 ppb |
| 2021 | 2.8 ppb |
| 2021 | 2 ppb |
| 2020 | 2 ppb |
| 2020 | 4 ppb |
| 2019 | 3 ppb |
| 2019 | 3 ppb |
| 2018 | 2 ppb |
| 2018 | 2 ppb |
| 2017 | 2.5 ppb |
| 2017 | 2.2 ppb |
| 2016 | 2.7 ppb |
Against other Colorado systems
Of the 1,025 Colorado systems with a lead result, the median latest reading is 1 ppb; 2 are over 15 ppb right now and 71 have gone over at some point. Castle Rock Town Of's 2 ppb sits at the 76th percentile in Colorado and the 73rd nationally (higher means more lead).
Neighbouring systems
29 other systems share Douglas County; 9 of them have a higher latest lead result than Castle Rock Town Of. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Highlands Ranch Wsd | 103,444 | 3 ppb |
| Parker Wsd | 75,949 | 2.6 ppb |
| Meridian Md | 23,415 | 0 (not detected) |
| Stonegate Md | 15,295 | 2 ppb |
| Roxborough Wsd | 13,765 | 5 ppb |
| Pinery Wwd | 12,901 | 0 (not detected) |
| Castle Pines North Md | 12,800 | 0 (not detected) |
| Sterling Ranch Cab | 11,501 | 0 (not detected) |
| Cottonwood Wsd | 10,867 | 0 (not detected) |
| Northern Douglas County Wsd | 6,160 | 0 (not detected) |
What to do in your house
Test your own tap with a certified lab first-draw sample; Castle Rock, CO may offer free or low-cost kits through the utility. If your own line is lead, replacing the private side runs about $1,200-$12,300 (EPA average about $4,700). Ask Castle Rock Town Of whether it covers that cost before hiring anyone - many utilities now do.
These figures describe homes the utility sampled, not your tap. Only your service line record or a test of your own water answers the question for your house. The lead result guide covers how utilities pick the homes they sample. Size matters more than most people expect: small vs large water systems.