Delta Mutual Water Company, CA
Lead reported as not detected
Latest 90th-percentile lead: reported as 0 (not detected) (monitoring period 2023-2025). 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.
Delta Mutual Water Company at a glance
Delta Mutual Water Company serves about 333 people through 119 service connections, which makes it a very small system under EPA's size classes. It is privately owned and draws groundwater, in Contra Costa County, California. EPA system ID: CA0707573; phone on file: 925-420-6260. They can tell you what your service line is made of and whether they pay to replace it.
Every lead result on file
That is down 12.4 ppb from 12.4 ppb in the period ending 2023. The highest 90th-percentile result EPA holds for Delta Mutual Water Company is 12.4 ppb across 4 monitoring periods, none of them over 15 ppb (1 over 10 ppb).
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 0 (not detected) |
| 2023 | 12.4 ppb over 10 |
| 2022 | 2 ppb |
| 2017 | 9 ppb |
Against other California systems
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. Delta Mutual Water Company's reported as 0 (not detected) sits at the 33rd percentile in California and the 19th 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 Delta Mutual Water Company. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Contra Costa Water District | 210,500 | 0 (not detected) |
| 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 | - |
Next steps for Oakley, CA
Look up your address in Delta Mutual Water Company'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 Delta Mutual Water Company 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. Small systems behave differently: why small systems go over more often.