CALIFORNIA WATER SERVICE - SAN CARLOS Water Quality Report
Serving roughly 35,344 people in San Mateo County, California.
Data current as of July 2026
🔍Straight from EPA
🧪Real Lab Results
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Results for CALIFORNIA WATER SERVICE - SAN CARLOS
1 water provider directly on file, serving roughly 35,344 people in San Mateo County, California.
Quick answer: CALIFORNIA WATER SERVICE - SAN CARLOS has no violations on file. One reading is worth knowing about: Dichloroaceticacid was measured at 27UG/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
Chloroform
Bromodichloromethane
Dibromochloromethane
Dichloroaceticacid
Trichloroaceticacid
Monochloroaceticacid
Utility CALIFORNIA WATER SERVICE - SAN CARLOSPopulation served 35,344Owner Private
No violations on file
Contaminants found
Metals
Naturally occurring or corrosion-related elements, e.g. lead, arsenic, copper
Lead Summary
Detected: 0.0058 mg/L (ppm)
12/31/2024
Disinfection Byproducts
Formed when chlorine used to disinfect water reacts with organic matter
Totalhaloaceticacids (HAA5)
Detected: 45 UG/L (ppb)
8/6/2025
TTHM
Detected: 51 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: 50 UG/L (ppb)
8/6/2025
One of the individual trihalomethane disinfection byproducts, formed when chlorine reacts with organic matter.
Bromodichloromethane
Detected: 0.94 UG/L (ppb)
8/6/2025
Dibromochloromethane
Detected: 1.4 UG/L (ppb)
2/3/2025
Other
Additional substances tested that don't fit neatly into the categories above
Dichloroaceticacid
Detected: 27 UG/L (ppb)
8/6/2025
Trichloroaceticacid
Detected: 16 UG/L (ppb)
8/6/2025
Monochloroaceticacid
Detected: 2.9 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.