Sandmound Mutual, 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.
Sandmound Mutual at a glance
Sandmound Mutual serves about 100 people through 110 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: CA0707556; phone on file: 760-936-2029. Ask them for your address in their service line inventory - every system had to publish one by Oct 2024.
Sandmound Mutual's lead record
Against the period ending 2024 (0 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Sandmound Mutual is 6.8 ppb across 4 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 0 (not detected) |
| 2024 | 0 (not detected) |
| 2020 | 6.8 ppb |
| 2020 | 6.8 ppb |
How Sandmound Mutual compares
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. Sandmound Mutual's reported as 0 (not detected) sits at the 18th percentile in California and the 9th nationally (higher means more lead). Systems reporting 0 tie at the bottom, so the rank mostly reflects size among them.
Nearby utilities
38 other systems share Contra Costa County; 10 of them have a higher latest lead result than Sandmound Mutual. 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 Bethel Island, CA
Look up your address in Sandmound Mutual'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 Sandmound Mutual whether it covers that cost before hiring anyone - many utilities now do. Its latest copper 90th percentile is 1500 ppb (copper action level 1,300 ppb).
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. A zero today does not rule out a jump later - the rules are tightening in 2027.