Rancho Santa Teresa Mw Co., CA
Exceeded the action level in the past
Latest 90th-percentile lead: 3.7 ppb (monitoring period 2025-2025). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. The latest result is under the action level, but this system has gone over 15 ppb before. Lead comes from pipes, not the source water, so a home with a lead service line can still be exposed. Test your own tap.
Who runs the water here
Rancho Santa Teresa Mw Co. serves about 102 people through 38 service connections, which makes it a very small system under EPA's size classes. It is privately owned and draws groundwater, in San Diego County, California. EPA system ID: CA3700918; phone on file: 858-354-5073. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Every lead result on file
That is up 1.9 ppb from 1.8 ppb in the period ending 2024. The highest 90th-percentile result EPA holds for Rancho Santa Teresa Mw Co. is 16.55 ppb across 11 monitoring periods, 1 of them over the 15 ppb action level.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 3.7 ppb |
| 2024 | 1.8 ppb |
| 2023 | 3.5 ppb |
| 2023 | 2.9 ppb |
| 2022 | 0 (not detected) |
| 2020 | 0 (not detected) |
| 2019 | 10.4 ppb over 10 |
| 2018 | 16.55 ppb over 15 |
| 2017 | 4.5 ppb |
| 2016 | 0 (not detected) |
| 2016 | 0 (not detected) |
How Rancho Santa Teresa Mw Co. 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. Rancho Santa Teresa Mw Co.'s 3.7 ppb sits at the 88th percentile in California and the 86th nationally (higher means more lead).
Nearby utilities
80 other systems share San Diego County; 5 of them have a higher latest lead result than Rancho Santa Teresa Mw Co.. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| San Diego, City Of | 1,408,937 | 0 (not detected) |
| Helix Water District | 277,918 | 0 (not detected) |
| Otay Water District | 242,155 | 0 (not detected) |
| Sweetwater Authority | 184,915 | 0 (not detected) |
| Oceanside, City Of | 174,340 | 0 (not detected) |
| Escondido, City Of | 137,044 | 1.1 ppb |
| Vista Irrigation District | 134,501 | 0 (not detected) |
| Vallecitos Wd | 114,700 | 0 (not detected) |
| Cal-Am Water Coronado | 106,000 | 2 ppb |
| Carlsbad Mwd | 96,371 | 0 (not detected) |
Your move
Test your own tap with a certified lab first-draw sample; Ramona, 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 Rancho Santa Teresa Mw 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. Why an old exceedance still matters: over the limit before, under it now.