Contra Costa Water District, CA
Lead reported as not detected
Latest 90th-percentile lead: reported as 0 (not detected) (monitoring period 2026-2028). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. The latest 90th-percentile result was reported as 0 (not detected at the lab's limit). That says the sampled homes were low, not that your home has no lead service line. Check your utility's service line inventory for your address.
About Contra Costa Water District
Contra Costa Water District serves about 210,500 people through 60,905 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 Contra Costa County, California. EPA system ID: CA0710003; phone on file: 925-688-8192. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Contra Costa Water District's lead record
That is down 3.1 ppb from 3.1 ppb in the period ending 2025. The highest 90th-percentile result EPA holds for Contra Costa Water District is 3.2 ppb across 7 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2028 | 0 (not detected) |
| 2025 | 3.1 ppb |
| 2025 | 3.1 ppb |
| 2022 | 3.2 ppb |
| 2022 | 3.2 ppb |
| 2019 | 0 (not detected) |
| 2016 | 0 (not detected) |
Where this result ranks
Of the 2,884 California systems with a lead result, the median latest reading is 0 ppb; 30 are over 15 ppb right now and 215 have gone over at some point. Contra Costa Water District's reported as 0 (not detected) sits at the 63rd percentile in California and the 40th nationally (higher means more lead). Systems reporting 0 tie at the bottom, so the rank mostly reflects size among them.
Other water systems in Contra Costa County
38 other systems share Contra Costa County; 10 of them have a higher latest lead result than Contra Costa Water District. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| City Of Antioch | 116,781 | 0 (not detected) |
| Brentwood | 64,513 | 0 (not detected) |
| City Of Pittsburg | 62,500 | 0 (not detected) |
| Diablo Water District | 47,158 | 1.9 ppb |
| City Of Martinez | 31,015 | 0 (not detected) |
| Golden State Water Company - Bay Point | 23,765 | 0.49 ppb |
| Town Of Discovery Bay | 16,790 | 0 (not detected) |
| Pleasantimes Mutual Water Co | 644 | 0.5 ppb |
| Clayton Palms Water | 549 | - |
| Willow Mobile Home Park | 481 | 10 ppb |
What to do in your house
Look up your address in Contra Costa Water District's service line inventory. If it says lead, galvanized or unknown, test your tap. If your own line is lead, replacing the private side runs about $1,200-$12,300 (EPA average about $4,700). Ask Contra Costa Water District 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. Why sampled homes are the worst-case ones is in the guide to reading the number. Small systems behave differently: why small systems go over more often.