First Mutual Water System, 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.
About First Mutual Water System
First Mutual Water System serves about 35 people through 13 service connections, which makes it a very small system under EPA's size classes. It is privately owned and draws groundwater, in Kern County, California. EPA system ID: CA1502569; phone on file: 661-435-5296. Ask them for your address in their service line inventory - every system had to publish one by Oct 2024.
Every lead result on file
Against the period ending 2022 (0.5 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for First Mutual Water System is 0.5 ppb across 4 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 0 (not detected) |
| 2022 | 0.5 ppb |
| 2019 | 0 (not detected) |
| 2016 | 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. First Mutual Water System's reported as 0 (not detected) sits at the 3rd percentile in California and the 1st nationally (higher means more lead). Systems reporting 0 tie at the bottom, so the rank mostly reflects size among them.
Other water systems in Kern County
165 other systems share Kern County; 75 of them have a higher latest lead result than First Mutual Water System. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Cws - Bakersfield | 268,129 | 2.8 ppb |
| Bakersfield, City Of | 171,108 | 1.3 ppb |
| Delano, City Of | 51,428 | 0 (not detected) |
| Oildale Mwc | 45,315 | 0 (not detected) |
| Indian Wells Valley W.D. | 41,474 | 0 (not detected) |
| Tejon Castac Wd - I5 & Laval Rd | 38,125 | 0 (not detected) |
| Antelope Valley E Kern Wtr Agy-Rosamond | 37,634 | - |
| Vaughn Wc Inc | 37,189 | 0 (not detected) |
| East Niles Csd | 32,517 | 1.4 ppb |
| Cws - North Garden | 27,634 | 4.2 ppb |
Next steps for Rosamond, CA
Look up your address in First Mutual Water System'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 First Mutual Water System 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. What a 90th-percentile result does and does not tell you: how to read a lead result. Small systems behave differently: why small systems go over more often.