- EPA's UCMR 5 testing looked for 30 contaminants here and found none.
- Lead, 90th percentile: 0 ppb at the latest result in EPA records for a monitoring period that ran on or after July 1, 2021, at or below EPA's 15 ppb action level (EPA SDWIS, monitoring period Jan 1, 2023–Dec 31, 2025). The 90th percentile is a system-wide measure from homes sampled under EPA's lead rule; it isn't a result for your home.
Public EPA test results
Can you drink Hillsborough tap water? What EPA records show
EPA CA4110016 · serves San Mateo County, CA · about 11,766 people (EPA SDWIS)
This report shows EPA's federal records for this water system: UCMR 5 testing, lead testing and violations. It isn't a test of the water at your tap, and it has no Water Score.
Public EPA test results
Town of Hillsborough (EPA CA4110016)
EPA data as of October 14, 2026. For Hillsborough's main utility, Town of Hillsborough: We found no health-based violations in EPA's records for this system (CA4110016) since July 1, 2021, as of October 14, 2026. PFOA and PFOS were not detected at or above EPA's reporting level in EPA's UCMR 5 testing.
What EPA records show for Town of Hillsborough, as of October 14, 2026
We found no health-based violations in EPA's records for this system (CA4110016) since July 1, 2021, as of October 14, 2026.
Source: EPA ECHO record for Town of Hillsborough (SDWIS). Data as of October 14, 2026.
Lead, 90th percentile: 0 ppb at the latest result in EPA records for a monitoring period that ran on or after July 1, 2021, at or below EPA's 15 ppb action level (EPA SDWIS, monitoring period Jan 1, 2023–Dec 31, 2025). The 90th percentile is a system-wide measure from homes sampled under EPA's lead rule; it isn't a result for your home.
EPA's UCMR 5 testing looked for 30 contaminants here and found none.
PFOA and PFOS were not detected at or above EPA's reporting level in EPA's UCMR 5 testing.
Source: EPA records (SDWIS, UCMR 5). SDWIS: data as of Oct 14, 2026. EPA UCMR 5 data, samples through June 2026.
Your water bill names your utility.
Does Town of Hillsborough use chloramine?
We didn't find chloramine in Town of Hillsborough's EPA treatment records. That's not a complete list; your utility's annual water quality report says which disinfectant it uses.