Mission Highlands Mutual Water Co., CA
Above the new 10 ppb level coming in 2027
Latest 90th-percentile lead: 13 ppb (monitoring period 2024-2026). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. Under the current 15 ppb rule this is not an exceedance, but it is above the 10 ppb action level that takes over in Nov 2027. Test your own tap; filter if your result shows lead.
Mission Highlands Mutual Water Co. at a glance
Mission Highlands Mutual Water Co. serves about 150 people through 69 service connections, which makes it a very small system under EPA's size classes. It is privately owned and draws groundwater, in Sonoma County, California. EPA system ID: CA4900563; phone on file: 415-710-8629. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Mission Highlands Mutual Water Co.'s lead record
That is up 13 ppb from 0 ppb in the period ending 2023. The highest 90th-percentile result EPA holds for Mission Highlands Mutual Water Co. is 13 ppb across 4 monitoring periods, none of them over 15 ppb (1 over 10 ppb).
| Period ending | 90th-percentile lead |
|---|---|
| 2026 | 13 ppb over 10 |
| 2023 | 0 (not detected) |
| 2022 | 0 (not detected) |
| 2016 | 5.45 ppb |
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. Mission Highlands Mutual Water Co.'s 13 ppb sits at the 99th percentile in California and the 98th nationally (higher means more lead).
Nearby utilities
128 other systems share Sonoma County; 0 of them have a higher latest lead result than Mission Highlands Mutual Water Co.. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Santa Rosa, City Of | 178,452 | 1.32 ppb |
| Petaluma, City Of | 61,427 | 0 (not detected) |
| Rohnert Park, City Of | 43,821 | 0 (not detected) |
| Windsor, Town Of | 25,561 | 0 (not detected) |
| Valley Of The Moon Water District | 23,140 | 0 (not detected) |
| Healdsburg, City Of | 10,972 | 0 (not detected) |
| Sonoma, City Of | 10,619 | 0 (not detected) |
| Cloverdale, City Of | 8,710 | 0 (not detected) |
| California-American Larkfield (Puc) | 7,911 | 6 ppb |
| Sebastopol, City Of | 7,522 | 0 (not detected) |
Your move
Test your own tap with a certified lab first-draw sample; Sonoma, CA 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 Mission Highlands Mutual Water Co. 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. See what changes at 10 ppb in 2027.