Larkin Woods Mutual Water Company, CA
Lead detected, under the action levels
Latest 90th-percentile lead: 2.5 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.
Larkin Woods Mutual Water Company at a glance
Larkin Woods Mutual Water Company serves about 34 people through 18 service connections, which makes it a very small system under EPA's size classes. It is privately owned and draws surface water, in Sonoma County, California. EPA system ID: CA4900582; phone on file: 214-926-5213. They can tell you what your service line is made of and whether they pay to replace it.
Lead results over time
That is down 1.7 ppb from 4.2 ppb in the period ending 2025. The highest 90th-percentile result EPA holds for Larkin Woods Mutual Water Company is 4.2 ppb across 4 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2026 | 2.5 ppb |
| 2025 | 4.2 ppb |
| 2024 | 2.5 ppb |
| 2024 | 0 (not detected) |
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. Larkin Woods Mutual Water Company's 2.5 ppb sits at the 81st percentile in California and the 77th nationally (higher means more lead).
Neighbouring systems
128 other systems share Sonoma County; 19 of them have a higher latest lead result than Larkin Woods Mutual Water Company. 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) |
What to do in your house
Test your own tap with a certified lab first-draw sample; Sebastopol, 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 Larkin Woods Mutual Water Company whether it covers that cost before hiring anyone - many utilities now do. Its latest copper 90th percentile is 1350 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. Size matters more than most people expect: small vs large water systems.