Serving roughly 27,072 people in Los Angeles County, California.
Data current as of July 2026
🔍Straight from EPA
🧪Real Lab Results
📅Updated Quarterly
🏠Local Expertise
Results for GSWC-SOUTH ARCADIA
1 water provider directly on file, serving roughly 27,072 people in Los Angeles County, California.
Quick answer: GSWC-SOUTH ARCADIA has no violations on file. One reading is worth knowing about: Aggressive Index was measured at 13AGGR, 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
PFOA
PFHXS
PFOS
TTHM
Bromoform
Bromodichloromethane
Dibromochloromethane
Chloroform
Dibromoaceticacid
Nitrate
Chromium, Hex
Trichloroethylene
Perchlorate
Chromium
Aggressive Index
Magnesium
Sodium
Calcium
Alkalinity, Total
Alkalinity, Bicarbonate
Hardness, Total (ASCACO3)
TDS
Sulfate
Chloride
Fluoride
Perfluorobutanesulfonicacid (PFBS)
Perfluorohexanesulfonicacid (PFHxS)
Perfluoroctanesulfonicacid (PFOS)
Perfluoroctanoicacid (PFOA)
Perfluorohexanoicacid (PFHXA)
Perfluorobutanoicacid (PFBA)
Perfluoropentanoicacid (PFPEA)
Turbidity
pH
Tetrachloroethylene
Conductivity (at 25°C)
Utility GSWC-SOUTH ARCADIAPopulation served 27,072Owner Private
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)
12/31/2023
Chromium, Hex
Detected: 7.5 UG/L (ppb)
5/30/2025
Chromium
Detected: 7.1 UG/L (ppb)
5/12/2025
Occurs in two forms — trivalent (an essential nutrient in trace amounts) and hexavalent (linked to increased cancer risk).
Disinfection Byproducts
Formed when chlorine used to disinfect water reacts with organic matter
TTHM
Detected: 4 UG/L (ppb)
10/22/2025
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.
Bromoform
Detected: 1.8 UG/L (ppb)
7/22/2025
Bromodichloromethane
Detected: 1.2 UG/L (ppb)
10/22/2025
Dibromochloromethane
Detected: 1.4 UG/L (ppb)
10/22/2025
Chloroform
Detected: 1.9 UG/L (ppb)
10/22/2025
One of the individual trihalomethane disinfection byproducts, formed when chlorine reacts with organic matter.
Inorganics
Common dissolved minerals and salts, e.g. nitrate, fluoride, chloride
Nitrate
Detected: 2.5 MG/L (ppm)
10/13/2025
Commonly from agricultural fertilizer runoff or septic systems. Above the legal limit, it's an immediate concern especially for infants.
Sulfate
Detected: 27 MG/L (ppm)
6/30/2025
Chloride
Detected: 15 MG/L (ppm)
6/30/2025
Fluoride
Detected: 0.78 MG/L (ppm)
5/30/2025
Often added deliberately for dental health; can also occur naturally.
Minerals
Everyday minerals that mainly affect taste and water hardness
Magnesium
Detected: 16 MG/L (ppm)
6/30/2025
Sodium
Detected: 22 MG/L (ppm)
6/30/2025
Calcium
Detected: 54 MG/L (ppm)
6/30/2025
Properties
General water characteristics like pH, hardness, and cloudiness (turbidity)
Hardness, Total (ASCACO3)
Detected: 200 MG/L (ppm)
6/30/2025
pH
Detected: 8.1 PH
6/30/2025
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
PFOA
Detected: 0.0052 µg/L (ppb)
7/10/2024
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
PFHXS
Detected: 0.0062 µg/L (ppb)
7/10/2024
PFOS
Detected: 0.016 µg/L (ppb)
7/10/2024
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
VOCs (Volatile Organic Compounds)
Industrial solvents and fuel-related chemicals that evaporate easily
Trichloroethylene
Detected: 0.96 UG/L (ppb)
10/13/2025
Tetrachloroethylene
Detected: 0.53 UG/L (ppb)
10/13/2025
Calculated Parameters
Values worked out mathematically from other test results, not measured directly
Alkalinity, Bicarbonate
Detected: 180 MG/L (ppm)
6/30/2025
Other
Additional substances tested that don't fit neatly into the categories above
Dibromoaceticacid
Detected: 1.3 UG/L (ppb)
7/22/2025
Perchlorate
Detected: 0.81 UG/L (ppb)
10/13/2025
Can occur naturally or from industrial/military sources; may interfere with thyroid function at elevated levels.
Aggressive Index
Detected: 13 AGGR
6/30/2025
Alkalinity, Total
Detected: 180 MG/L (ppm)
6/30/2025
TDS
Detected: 280 MG/L (ppm)
6/30/2025
Perfluorobutanesulfonicacid (PFBS)
Detected: 2.9 NG/L (ppt)
9/11/2025
Perfluorohexanesulfonicacid (PFHxS)
Detected: 5.8 NG/L (ppt)
9/11/2025
Perfluoroctanesulfonicacid (PFOS)
Detected: 15 NG/L (ppt)
9/11/2025
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
Perfluoroctanoicacid (PFOA)
Detected: 8 NG/L (ppt)
9/11/2025
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
Perfluorohexanoicacid (PFHXA)
Detected: 2.9 NG/L (ppt)
9/11/2025
Perfluorobutanoicacid (PFBA)
Detected: 5.9 NG/L (ppt)
9/11/2025
Perfluoropentanoicacid (PFPEA)
Detected: 2.4 NG/L (ppt)
9/11/2025
Turbidity
Detected: 0.2 NTU
6/30/2025
A measure of water cloudiness from suspended particles.
Conductivity (at 25°C)
Detected: 470 UMHO/CM
6/30/2025
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.