Serving roughly 11,766 people in San Mateo County, California.
Data current as of July 2026
🔍Straight from EPA
🧪Real Lab Results
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Results for TOWN OF HILLSBOROUGH
1 water provider directly on file, serving roughly 11,766 people in San Mateo County, California.
Quick answer: TOWN OF HILLSBOROUGH has no violations on file. One reading is worth knowing about: Chloroform was measured at 66.3UG/L, among the highest of the 113 providers on file in this area. It's the most notable figure in this system's record among its 113 local peers.
Lead Summary
Totalhaloaceticacids (HAA5)
TTHM
Lead
Chloroform
Bromodichloromethane
Dibromochloromethane
Dichloroaceticacid
Trichloroaceticacid
Copper, Free
Utility TOWN OF HILLSBOROUGHPopulation served 11,766Owner Local government
No violations on file
Contaminants found
Metals
Naturally occurring or corrosion-related elements, e.g. lead, arsenic, copper
Lead Summary
Detected: 0 mg/L (ppm)
12/31/2025
Lead
Detected: 6.3 UG/L (ppb)
8/11/2025
A metal that can leach from old pipes, solder, and fixtures. Current medical guidance holds there is no truly safe level of lead exposure, especially for children and pregnant women.
Copper, Free
Detected: 103 UG/L (ppb)
8/12/2025
Disinfection Byproducts
Formed when chlorine used to disinfect water reacts with organic matter
Totalhaloaceticacids (HAA5)
Detected: 38.4 UG/L (ppb)
8/6/2025
TTHM
Detected: 67.5 UG/L (ppb)
8/6/2025
A group of disinfection byproducts formed when chlorine reacts with organic matter. Long-term exposure above the legal limit has been linked to increased cancer risk in some studies.
Chloroform
Detected: 66.3 UG/L (ppb)
8/6/2025
One of the individual trihalomethane disinfection byproducts, formed when chlorine reacts with organic matter.
Bromodichloromethane
Detected: 1.26 UG/L (ppb)
8/6/2025
Dibromochloromethane
Detected: 1.82 UG/L (ppb)
2/5/2025
Other
Additional substances tested that don't fit neatly into the categories above
Dichloroaceticacid
Detected: 19 UG/L (ppb)
8/6/2025
Trichloroaceticacid
Detected: 19.4 UG/L (ppb)
8/6/2025
Filtration considerations: See the table below for how whole-house carbon, under-sink reverse osmosis, and under-sink carbon systems compare against what's actually on file here. These are general system types, not a specific product recommendation.