Serving roughly 20,283 people in Los Angeles County, California.
Data current as of July 2026
🔍Straight from EPA
🧪Real Lab Results
📅Updated Quarterly
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Results for NORWALK - CITY, WATER DEPT.
1 water provider directly on file, serving roughly 20,283 people in Los Angeles County, California.
Quick answer: NORWALK - CITY, WATER DEPT. has no violations on file. One reading is worth knowing about: Calcium was measured at 144MG/L, among the highest of the 601 providers on file in this area. It's the most notable figure in this system's record among its 601 local peers.
Lead Summary
Lithium
PFOS
PFOA
PFHXS
PFBA
PFPEA
Totalhaloaceticacids (HAA5)
TTHM
Chloroform
Bromoform
Bromodichloromethane
Dibromochloromethane
Dichloroaceticacid
Trichloroaceticacid
Dibromoaceticacid
Aggressive Index
Magnesium
Calcium
Potassium
Sodium
Hardness, Total (ASCACO3)
Alkalinity, Total
Alkalinity, Bicarbonate
TDS
Chloride
Sulfate
Fluoride
Nitrate-Nitrite
Nitrate
Perfluorobutanesulfonicacid (PFBS)
Perfluorohexanesulfonicacid (PFHxS)
Perfluoroctanesulfonicacid (PFOS)
Perfluoroctanoicacid (PFOA)
Perfluorohexanoicacid (PFHXA)
Perfluorobutanoicacid (PFBA)
Perfluoropentanoicacid (PFPEA)
Turbidity
pH
1, 4-Dioxane
Chromium, Hex
Trichloroethylene
Tetrachloroethylene
Benzene
Conductivity (at 25°C)
Utility NORWALK - CITY, WATER DEPT.Population served 20,283Owner Local government
Naturally occurring or corrosion-related elements, e.g. lead, arsenic, copper
Lead Summary
Detected: 0 mg/L (ppm)
12/31/2022
Chromium, Hex
Detected: 1.6 UG/L (ppb)
6/27/2025
Disinfection Byproducts
Formed when chlorine used to disinfect water reacts with organic matter
Totalhaloaceticacids (HAA5)
Detected: 7.5 UG/L (ppb)
8/27/2025
TTHM
Detected: 32.8 UG/L (ppb)
8/27/2025
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: 6.7 UG/L (ppb)
8/27/2025
One of the individual trihalomethane disinfection byproducts, formed when chlorine reacts with organic matter.
Bromoform
Detected: 4.4 UG/L (ppb)
8/27/2025
Bromodichloromethane
Detected: 9.5 UG/L (ppb)
8/27/2025
Dibromochloromethane
Detected: 12.2 UG/L (ppb)
8/27/2025
Inorganics
Common dissolved minerals and salts, e.g. nitrate, fluoride, chloride
Chloride
Detected: 83 MG/L (ppm)
7/21/2025
Sulfate
Detected: 220 MG/L (ppm)
7/21/2025
Fluoride
Detected: 0.26 MG/L (ppm)
7/21/2025
Often added deliberately for dental health; can also occur naturally.
Nitrate-Nitrite
Detected: 2.3 MG/L (ppm)
7/21/2025
Nitrate
Detected: 2.3 MG/L (ppm)
7/21/2025
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: 30 MG/L (ppm)
7/21/2025
Calcium
Detected: 144 MG/L (ppm)
7/21/2025
Potassium
Detected: 5.2 MG/L (ppm)
7/21/2025
Sodium
Detected: 57 MG/L (ppm)
7/21/2025
Properties
General water characteristics like pH, hardness, and cloudiness (turbidity)
Hardness, Total (ASCACO3)
Detected: 482 MG/L (ppm)
7/21/2025
pH
Detected: 7.53 PH
7/21/2025
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: 26 µg/L (ppb)
11/20/2024
Occurs naturally in some groundwater. Not currently federally regulated in drinking water.
PFOS
Detected: 0.022 µg/L (ppb)
8/26/2024
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
PFOA
Detected: 0.0049 µg/L (ppb)
8/26/2024
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
PFHXS
Detected: 0.0073 µg/L (ppb)
8/26/2024
PFBA
Detected: 0.0055 µg/L (ppb)
8/26/2024
PFPEA
Detected: 0.0034 µg/L (ppb)
8/26/2024
VOCs (Volatile Organic Compounds)
Industrial solvents and fuel-related chemicals that evaporate easily
Trichloroethylene
Detected: 2.2 UG/L (ppb)
7/21/2025
Tetrachloroethylene
Detected: 1.5 UG/L (ppb)
7/21/2025
Petroleum Compounds
Substances associated with fuel or petroleum contamination
Benzene
Detected: 0.69 UG/L (ppb)
1/13/2025
Calculated Parameters
Values worked out mathematically from other test results, not measured directly
Alkalinity, Bicarbonate
Detected: 380 MG/L (ppm)
7/21/2025
Other
Additional substances tested that don't fit neatly into the categories above
Dichloroaceticacid
Detected: 4.6 UG/L (ppb)
8/27/2025
Trichloroaceticacid
Detected: 1.7 UG/L (ppb)
8/27/2025
Dibromoaceticacid
Detected: 1.2 UG/L (ppb)
8/27/2025
Aggressive Index
Detected: 12.6 AGGR
7/21/2025
Alkalinity, Total
Detected: 310 MG/L (ppm)
7/21/2025
TDS
Detected: 800 MG/L (ppm)
7/21/2025
Perfluorobutanesulfonicacid (PFBS)
Detected: 2.5 NG/L (ppt)
7/21/2025
Perfluorohexanesulfonicacid (PFHxS)
Detected: 9.1 NG/L (ppt)
7/21/2025
Perfluoroctanesulfonicacid (PFOS)
Detected: 31 NG/L (ppt)
7/21/2025
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
Perfluoroctanoicacid (PFOA)
Detected: 7.4 NG/L (ppt)
7/21/2025
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
Perfluorohexanoicacid (PFHXA)
Detected: 2.7 NG/L (ppt)
1/13/2025
Perfluorobutanoicacid (PFBA)
Detected: 5.6 NG/L (ppt)
7/21/2025
Perfluoropentanoicacid (PFPEA)
Detected: 2.2 NG/L (ppt)
7/21/2025
Turbidity
Detected: 0.15 NTU
7/21/2025
A measure of water cloudiness from suspended particles.
1, 4-Dioxane
Detected: 2.1 UG/L (ppb)
10/1/2025
Conductivity (at 25°C)
Detected: 1100 UMHO/CM
7/21/2025
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.