Serving roughly 42,631 people in San Mateo County, California.
Data current as of July 2026
🔍Straight from EPA
🧪Real Lab Results
📅Updated Quarterly
🏠Local Expertise
Results for CITY OF SAN BRUNO
1 water provider directly on file, serving roughly 42,631 people in San Mateo County, California.
Quick answer: CITY OF SAN BRUNO has no violations on file. One reading is worth knowing about: Chromium, Hex was measured at 4.37UG/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
Lithium
TDS
Aggressive Index
Magnesium
Potassium
Sodium
Calcium
Alkalinity, Total
Alkalinity, Bicarbonate
Hardness, Total (ASCACO3)
Sulfate
Chloride
Fluoride
Nitrate
pH
Vanadium, Total
Manganese
Chromium, Hex
Conductivity (at 25°C)
Totalhaloaceticacids (HAA5)
TTHM
Lead
Chloroform
Bromodichloromethane
Dibromochloromethane
Dichloroaceticacid
Trichloroaceticacid
Dibromoaceticacid
Copper, Free
Utility CITY OF SAN BRUNOPopulation served 42,631Owner Local government
Naturally occurring or corrosion-related elements, e.g. lead, arsenic, copper
Lead Summary
Detected: 0 mg/L (ppm)
12/31/2025
Vanadium, Total
Detected: 7.8 UG/L (ppb)
1/15/2025
Manganese
Detected: 57 UG/L (ppb)
10/6/2025
Mainly a taste/staining concern at typical levels; long-term neurological research at high chronic exposure is ongoing.
Chromium, Hex
Detected: 4.37 UG/L (ppb)
10/6/2025
Lead
Detected: 5.9 UG/L (ppb)
8/20/2025
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: 58 UG/L (ppb)
8/22/2025
Disinfection Byproducts
Formed when chlorine used to disinfect water reacts with organic matter
Totalhaloaceticacids (HAA5)
Detected: 8.2 UG/L (ppb)
8/13/2025
TTHM
Detected: 15.81 UG/L (ppb)
8/13/2025
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: 7.39 UG/L (ppb)
8/13/2025
One of the individual trihalomethane disinfection byproducts, formed when chlorine reacts with organic matter.
Bromodichloromethane
Detected: 5.38 UG/L (ppb)
8/13/2025
Dibromochloromethane
Detected: 3.04 UG/L (ppb)
8/13/2025
Inorganics
Common dissolved minerals and salts, e.g. nitrate, fluoride, chloride
Sulfate
Detected: 27 MG/L (ppm)
1/15/2025
Chloride
Detected: 63 MG/L (ppm)
1/15/2025
Fluoride
Detected: 0.15 MG/L (ppm)
1/15/2025
Often added deliberately for dental health; can also occur naturally.
Nitrate
Detected: 1.4 MG/L (ppm)
1/15/2025
Commonly from agricultural fertilizer runoff or septic systems. Above the legal limit, it's an immediate concern especially for infants.
Minerals
Everyday minerals that mainly affect taste and water hardness
Magnesium
Detected: 19 MG/L (ppm)
1/15/2025
Potassium
Detected: 3.1 MG/L (ppm)
1/15/2025
Sodium
Detected: 39 MG/L (ppm)
1/15/2025
Calcium
Detected: 29 MG/L (ppm)
1/15/2025
Properties
General water characteristics like pH, hardness, and cloudiness (turbidity)
Hardness, Total (ASCACO3)
Detected: 152 MG/L (ppm)
1/15/2025
pH
Detected: 7.33 PH
1/15/2025
A measure of how acidic or basic the water is (7 is neutral). Affects taste and plumbing, not a direct health measure.
PFAS & Emerging Contaminants
Human-made "forever chemicals" and other substances not yet fully regulated
Lithium
Detected: 33 µg/L (ppb)
4/10/2025
Occurs naturally in some groundwater. Not currently federally regulated in drinking water.
Calculated Parameters
Values worked out mathematically from other test results, not measured directly
Alkalinity, Bicarbonate
Detected: 120 MG/L (ppm)
1/15/2025
Other
Additional substances tested that don't fit neatly into the categories above
TDS
Detected: 550 MG/L (ppm)
10/6/2025
Aggressive Index
Detected: 11.27 AGGR
1/15/2025
Alkalinity, Total
Detected: 120 MG/L (ppm)
1/15/2025
Conductivity (at 25°C)
Detected: 520 UMHO/CM
1/15/2025
Dichloroaceticacid
Detected: 4.8 UG/L (ppb)
8/13/2025
Trichloroaceticacid
Detected: 1.7 UG/L (ppb)
8/13/2025
Dibromoaceticacid
Detected: 1.7 UG/L (ppb)
8/13/2025
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.