Palomar Observatory, CA
Lead reported as not detected
Latest 90th-percentile lead: reported as 0 (not detected) (monitoring period 2021-2023). 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 Palomar Observatory
Palomar Observatory serves about 20 people through 26 service connections, which makes it a very small system under EPA's size classes. It is owned by the state and draws groundwater, in San Diego County, California. EPA system ID: CA3702236; phone on file: 760-742-2100. Ask them for your address in their service line inventory - every system had to publish one by Oct 2024.
Lead results over time
Against the period ending 2023 (0 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Palomar Observatory is 9 ppb across 4 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2023 | 0 (not detected) |
| 2023 | 0 (not detected) |
| 2020 | 3 ppb |
| 2017 | 9 ppb |
How Palomar Observatory 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. Palomar Observatory's reported as 0 (not detected) sits at the 0th percentile in California and the 0th nationally (higher means more lead). Systems reporting 0 tie at the bottom, so the rank mostly reflects size among them.
Neighbouring systems
80 other systems share San Diego County; 29 of them have a higher latest lead result than Palomar Observatory. 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) |
Next steps for Palomar Mountain, CA
Look up your address in Palomar Observatory'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 Palomar Observatory 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.