Town Of Hillsborough, 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 Town Of Hillsborough
Town Of Hillsborough serves about 11,766 people through 4,303 service connections, which makes it a large system under EPA's size classes. It is owned by a local government (city, town, county or district) and draws surface water, in San Mateo County, California. EPA system ID: CA4110016; phone on file: 650-375-7487. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Every lead result on file
That is down 6.5 ppb from 6.5 ppb in the period ending 2022. The highest 90th-percentile result EPA holds for Town Of Hillsborough is 7 ppb across 4 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 0 (not detected) |
| 2022 | 6.5 ppb |
| 2019 | 7 ppb |
| 2016 | 5.8 ppb |
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. Town Of Hillsborough's reported as 0 (not detected) sits at the 54th percentile in California and the 37th nationally (higher means more lead). Systems reporting 0 tie at the bottom, so the rank mostly reflects size among them.
Nearby utilities
35 other systems share San Mateo County; 17 of them have a higher latest lead result than Town Of Hillsborough. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| California Water Service - San Mateo | 103,536 | 4.4 ppb |
| City Of Daly City | 102,593 | 0 (not detected) |
| City Of Redwood City | 90,043 | 0 (not detected) |
| California Water Service-S San Francisco | 62,609 | 4.1 ppb |
| California Water Service - Bear Gulch | 60,382 | 4 ppb |
| City Of San Bruno | 42,631 | 0 (not detected) |
| North Coast County Water Dist | 38,546 | 0 (not detected) |
| Estero Municipal Improvement District | 36,556 | 0 (not detected) |
| California Water Service - San Carlos | 34,801 | 5.8 ppb |
| City Of Burlingame | 32,453 | 6.3 ppb |
Next steps for Hillsborough, CA
Look up your address in Town Of Hillsborough'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 Town Of Hillsborough 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. Small systems behave differently: why small systems go over more often.