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Water Quality Lookup / California / Santa Clara County
EPA SDWIS ยท Santa Clara County, California ยท 320 providers profiled

Santa Clara County, CA Water Quality Report

Santa Clara County is served by 320 major public water systems on file with the EPA.

Data current as of July 2026
๐Ÿ”Straight from EPA
๐ŸงชReal Lab Results
๐Ÿ“…Updated Quarterly
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Results for Santa Clara County, CA

320 water providers on file for this county, sorted by population served.

Quick answer: Santa Clara County has 320 water providers profiled, sorted by population served.

Violations on file

Nitrate
Older/archived health-based violation
Found at 18 of 320 providers
Commonly from agricultural fertilizer runoff or septic systems. Above the legal limit, it's an immediate concern especially for infants.
Coliform (TCR)
Older/archived health-based violation
Found at 12 of 320 providers
Surface Water Treatment Rule
Older/archived health-based violation
Found at 2 of 320 providers
Bhc-Gamma
Older/archived health-based violation
Found at 1 of 320 providers
Methoxychlor
Older/archived health-based violation
Found at 1 of 320 providers
Toxaphene
Older/archived health-based violation
Found at 1 of 320 providers
Endrin
Older/archived health-based violation
Found at 1 of 320 providers
2, 4, 5-Tp
Older/archived health-based violation
Found at 1 of 320 providers
2, 4-D
Older/archived health-based violation
Found at 1 of 320 providers
Lead And Copper Rule
Older/archived health-based violation
Found at 1 of 320 providers
Lead And Copper Rule Revisions
Currently open health violation
Found at 12 of 320 providers

Contaminants found

Metals
Naturally occurring or corrosion-related elements, e.g. lead, arsenic, copper
Lead Summary
Detected: 0.0182 mg/L (ppm)
Found at 109 providers
Chromium, Hex
Detected: 4.8 UG/L (ppb)
Found at 25 providers
Lead
Detected: 36.4 UG/L (ppb)
Found at 20 providers
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: 880 UG/L (ppb)
Found at 39 providers
Iron
Detected: 3420 UG/L (ppb)
Found at 17 providers
Mostly an aesthetic issue (metallic taste, staining) rather than a health concern at typical levels.
Manganese
Detected: 1000 UG/L (ppb)
Found at 14 providers
Mainly a taste/staining concern at typical levels; long-term neurological research at high chronic exposure is ongoing.
Nickel
Detected: 8.9 UG/L (ppb)
Found at 4 providers
Silver
Detected: 1.6 UG/L (ppb)
6/9/2025
Barium
Detected: 145 UG/L (ppb)
Found at 18 providers
Selenium
Detected: 1.7 UG/L (ppb)
Found at 4 providers
Aluminum
Detected: 500 UG/L (ppb)
Found at 6 providers
Chromium
Detected: 5.5 UG/L (ppb)
Found at 5 providers
Occurs in two forms โ€” trivalent (an essential nutrient in trace amounts) and hexavalent (linked to increased cancer risk).
Zinc
Detected: 87 UG/L (ppb)
Found at 4 providers
Copper Summary
Detected: 605 mg/L (ppm)
Found at 7 providers
Arsenic
Detected: 2.2 UG/L (ppb)
Found at 4 providers
Occurs naturally in some groundwater. Long-term exposure above the legal limit (10 ppb) has been linked to increased cancer risk and cardiovascular disease.
Strontium
Detected: 360 UG/L (ppb)
6/9/2025
Vanadium, Total
Detected: 8.8 UG/L (ppb)
Found at 2 providers
Disinfection Byproducts
Formed when chlorine used to disinfect water reacts with organic matter
Totalhaloaceticacids (HAA5)
Detected: 51.8 UG/L (ppb)
Found at 26 providers
TTHM
Detected: 102 UG/L (ppb)
Found at 46 providers
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: 62.34 UG/L (ppb)
Found at 32 providers
One of the individual trihalomethane disinfection byproducts, formed when chlorine reacts with organic matter.
Bromodichloromethane
Detected: 16 UG/L (ppb)
Found at 40 providers
Dibromochloromethane
Detected: 42 UG/L (ppb)
Found at 45 providers
Bromoform
Detected: 44 UG/L (ppb)
Found at 32 providers
Inorganics
Common dissolved minerals and salts, e.g. nitrate, fluoride, chloride
Nitrate
Detected: 12 MG/L (ppm)
Found at 65 providers
Commonly from agricultural fertilizer runoff or septic systems. Above the legal limit, it's an immediate concern especially for infants.
Chloride
Detected: 69 MG/L (ppm)
Found at 20 providers
Sulfate
Detected: 97 MG/L (ppm)
Found at 20 providers
Fluoride
Detected: 0.27 MG/L (ppm)
Found at 20 providers
Often added deliberately for dental health; can also occur naturally.
Nitrate-Nitrite
Detected: 10 MG/L (ppm)
Found at 23 providers
Boron, Total
Detected: 910 UG/L (ppb)
Found at 7 providers
Minerals
Everyday minerals that mainly affect taste and water hardness
Magnesium
Detected: 42 MG/L (ppm)
Found at 19 providers
Potassium
Detected: 2.5 MG/L (ppm)
Found at 15 providers
Sodium
Detected: 124 MG/L (ppm)
Found at 20 providers
Calcium
Detected: 95 MG/L (ppm)
Found at 19 providers
Properties
General water characteristics like pH, hardness, and cloudiness (turbidity)
Gross Alpha Particle Activity
Detected: 4.39 PCI/L
Found at 12 providers
Langelier Index (pH(s))
Detected: 1.09 LANG
Found at 12 providers
Hardness, Total (ASCACO3)
Detected: 331 MG/L (ppm)
Found at 19 providers
pH
Detected: 8.6 PH
Found at 15 providers
A measure of how acidic or basic the water is (7 is neutral). Affects taste and plumbing, not a direct health measure.
pH, Field
Detected: 8.6 PH
Found at 3 providers
Orthophosphate
Detected: 1.04 MG/L (ppm)
9/17/2025
PFAS & Emerging Contaminants
Human-made "forever chemicals" and other substances not yet fully regulated
Lithium
Detected: 18.8 ยตg/L (ppb)
Found at 9 providers
Occurs naturally in some groundwater. Not currently federally regulated in drinking water.
PFHXS
Detected: 0.008 ยตg/L (ppb)
Found at 5 providers
PFPEA
Detected: 0.0047 ยตg/L (ppb)
Found at 3 providers
PFHXA
Detected: 0.0045 ยตg/L (ppb)
Found at 3 providers
PFBS
Detected: 0.004 ยตg/L (ppb)
6/25/2025
PFHPA
Detected: 0.0036 ยตg/L (ppb)
12/17/2024
PFOS
Detected: 0.0062 ยตg/L (ppb)
Found at 3 providers
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
PFOA
Detected: 0.0055 ยตg/L (ppb)
6/25/2025
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
Bromide
Detected: 0.2 MG/L (ppm)
Found at 2 providers
Dichlorodifluoromethane
Detected: 2.6 UG/L (ppb)
3/12/2025
Tetrachloroethylene
Detected: 0.85 UG/L (ppb)
9/29/2025
Calculated Parameters
Values worked out mathematically from other test results, not measured directly
Alkalinity, Bicarbonate
Detected: 316 MG/L (ppm)
Found at 19 providers
Alkalinity, Carbonate
Detected: 30 MG/L (ppm)
3/19/2025
Other
Additional substances tested that don't fit neatly into the categories above
Perchlorate
Detected: 4.7 UG/L (ppb)
Found at 12 providers
Can occur naturally or from industrial/military sources; may interfere with thyroid function at elevated levels.
Dichloroaceticacid
Detected: 33.6 UG/L (ppb)
Found at 27 providers
Trichloroaceticacid
Detected: 20.4 UG/L (ppb)
Found at 24 providers
Monochloroaceticacid
Detected: 3.2 UG/L (ppb)
Found at 8 providers
Aggressive Index
Detected: 12.66 AGGR
Found at 15 providers
Langelier Index (Source Temp.)
Detected: 0.5 LANG
Found at 9 providers
Alkalinity, Total
Detected: 280 MG/L (ppm)
Found at 19 providers
TDS
Detected: 618 MG/L (ppm)
Found at 21 providers
Turbidity
Detected: 14 NTU
Found at 15 providers
A measure of water cloudiness from suspended particles.
Conductivity (at 25ยฐC)
Detected: 825 UMHO/CM
Found at 23 providers
Color
Detected: 20 UNITS
Found at 11 providers
Odor
Detected: 2 TON
Found at 4 providers
Dibromoaceticacid
Detected: 15.1 UG/L (ppb)
Found at 23 providers
Temperature (CENTIGRADE)
Detected: 25.1 C
Found at 3 providers
Silica
Detected: 30 MG/L (ppm)
Found at 2 providers
Perfluorobutanesulfonicacid (PFBS)
Detected: 5.3 NG/L (ppt)
Found at 5 providers
Perfluoroctanesulfonicacid (PFOS)
Detected: 16 NG/L (ppt)
Found at 6 providers
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
Perfluoroctanoicacid (PFOA)
Detected: 21 NG/L (ppt)
Found at 3 providers
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
Perfluorobutanoicacid (PFBA)
Detected: 13 NG/L (ppt)
Found at 5 providers
Perfluoropentanoicacid (PFPEA)
Detected: 4 NG/L (ppt)
Found at 4 providers
Radium-228
Detected: 1.53 PCI/L
Found at 11 providers
Combined Radium (-226 & -228)
Detected: 1.61 PCI/L
Found at 7 providers
A naturally occurring radioactive element found in some groundwater.
Perfluorohexanesulfonicacid (PFHxS)
Detected: 5.1 NG/L (ppt)
Found at 5 providers
Monobromoaceticacid
Detected: 1.9 UG/L (ppb)
Found at 4 providers
Perfluorohexanoicacid (PFHXA)
Detected: 11 NG/L (ppt)
Found at 4 providers
Cyanide
Detected: 6 UG/L (ppb)
Found at 2 providers
Perfluoroheptanoicacid (PFHPA)
Detected: 14 NG/L (ppt)
Found at 2 providers
Chlorate
Detected: 280 UG/L (ppb)
9/11/2025
Carbondioxide
Detected: 40000 UG/L (ppb)
Found at 2 providers
Carbon, Total
Detected: 1.81 MG/L (ppm)
Found at 3 providers
Trichlorotrifluoroethane
Detected: 0.47 UG/L (ppb)
8/11/2025
Perfluorononanoicacid (PFNA)
Detected: 15 NG/L (ppt)
5/21/2025
Perfluorodecanoicacid (PFDA)
Detected: 13 NG/L (ppt)
5/21/2025
Perfluorododecanoicacid (PFDOA)
Detected: 12 NG/L (ppt)
5/21/2025
Perfluoroundecanoicacid (PFUNA)
Detected: 13 NG/L (ppt)
5/21/2025
11cl-Pf3ouds
Detected: 20 NG/L (ppt)
5/21/2025
9cl-Pf3ons
Detected: 21 NG/L (ppt)
5/21/2025
Adona
Detected: 16 NG/L (ppt)
5/21/2025
Hfpo-Da
Detected: 11 NG/L (ppt)
5/21/2025
Perfluorooctanesulfonicacid6:2fts
Detected: 13 NG/L (ppt)
5/21/2025
Perfluorohexanesulfonicacid4:2fts
Detected: 11 NG/L (ppt)
5/21/2025
Perfluorodecanesulfonicacid8:2fts
Detected: 16 NG/L (ppt)
5/21/2025
Perfluoropfmpa
Detected: 11 NG/L (ppt)
5/21/2025
Perfluoropfmba
Detected: 12 NG/L (ppt)
5/21/2025
Perfluoropfeesa
Detected: 13 NG/L (ppt)
5/21/2025
Nonafluoronfdha
Detected: 8.3 NG/L (ppt)
5/21/2025
Perfluoropentanesulfonicacid (PFPES)
Detected: 9.7 NG/L (ppt)
5/21/2025
Perfluoroheptanesulfonicacid (PFHPS)
Detected: 14 NG/L (ppt)
5/21/2025
Asbestos
Detected: 6.7 MFL
5/20/2025
Filtration considerations: General system types, not a specific product recommendation.
Contaminant Whole-House Carbon Under-Sink RO Under-Sink Carbon
Total Trihalomethanes (TTHM)YesYesYes
Haloacetic Acids (HAA5)YesYesYes
ChloroformYesYesYes
Chlorine / TasteYesYesYes
Sediment / TurbidityYesYesYes
TrichloroethyleneYesYesYes
TetrachloroethyleneYesYesYes
cis-1,2-DichloroethyleneYesYesYes
1,1-DichloroethyleneYesYesYes
BromoformYesYesYes
BromodichloromethaneYesYesYes
DibromochloromethaneYesYesYes
1,1,2-TrichloroethaneYesYesYes
Vinyl ChlorideYesYesYes
Carbon TetrachlorideYesYesYes
BenzeneYesYesYes
TolueneYesYesYes
XyleneYesYesYes
Totalhaloaceticacids (HAA5)YesYesYes
BromideYesYesYes
DichlorodifluoromethaneYesYesYes
LeadPartialYesPartial
ArsenicPartialYesPartial
Chromium-6 (Hexavalent)PartialYesPartial
CopperPartialYesPartial
Combined UraniumPartialYesPartial
PFOAPartialYes*Partial
PFOSPartialYes*Partial
NitratePartialYesPartial
Combined RadiumPartialYesPartial
Chromium, HexPartialYesPartial
PerchloratePartialYesPartial
Copper, FreePartialYesPartial
DichloroaceticacidPartialYesPartial
TrichloroaceticacidPartialYesPartial
MonochloroaceticacidPartialYesPartial
Aggressive IndexPartialYesPartial
Langelier Index (Source Temp.)PartialYesPartial
Alkalinity, TotalPartialYesPartial
TDSPartialYesPartial
ChloridePartialYesPartial
SulfatePartialYesPartial
FluoridePartialYesPartial
IronPartialYesPartial
ManganesePartialYesPartial
NickelPartialYesPartial
SilverPartialYesPartial
BariumPartialYesPartial
SeleniumPartialYesPartial
Conductivity (at 25ยฐC)PartialYesPartial
AluminumPartialYesPartial
Nitrate-NitritePartialYesPartial
ColorPartialYesPartial
OdorPartialYesPartial
ChromiumPartialYesPartial
ZincPartialYesPartial
DibromoaceticacidPartialYesPartial
Temperature (CENTIGRADE)PartialYesPartial
SilicaPartialYesPartial
Perfluorobutanesulfonicacid (PFBS)PartialYesPartial
Perfluoroctanesulfonicacid (PFOS)PartialYesPartial
Perfluoroctanoicacid (PFOA)PartialYesPartial
Perfluorobutanoicacid (PFBA)PartialYesPartial
Perfluoropentanoicacid (PFPEA)PartialYesPartial
Boron, TotalPartialYesPartial
Combined Radium (-226 & -228)PartialYesPartial
LithiumPartialYes*Partial
Perfluorohexanesulfonicacid (PFHxS)PartialYesPartial
MonobromoaceticacidPartialYesPartial
PFHXSPartialYes*Partial
Perfluorohexanoicacid (PFHXA)PartialYesPartial
StrontiumPartialYesPartial
Vanadium, TotalPartialYesPartial
CyanidePartialYesPartial
PFPEAPartialYes*Partial
PFHXAPartialYes*Partial
PFBSPartialYes*Partial
PFHPAPartialYes*Partial
Perfluoroheptanoicacid (PFHPA)PartialYesPartial
ChloratePartialYesPartial
CarbondioxidePartialYesPartial
Carbon, TotalPartialYesPartial
TrichlorotrifluoroethanePartialYesPartial
Perfluorononanoicacid (PFNA)PartialYesPartial
Perfluorodecanoicacid (PFDA)PartialYesPartial
Perfluorododecanoicacid (PFDOA)PartialYesPartial
Perfluoroundecanoicacid (PFUNA)PartialYesPartial
11cl-Pf3oudsPartialYesPartial
9cl-Pf3onsPartialYesPartial
AdonaPartialYesPartial
Hfpo-DaPartialYesPartial
Perfluorooctanesulfonicacid6:2ftsPartialYesPartial
Perfluorohexanesulfonicacid4:2ftsPartialYesPartial
Perfluorodecanesulfonicacid8:2ftsPartialYesPartial
PerfluoropfmpaPartialYesPartial
PerfluoropfmbaPartialYesPartial
PerfluoropfeesaPartialYesPartial
NonafluoronfdhaPartialYesPartial
Perfluoropentanesulfonicacid (PFPES)PartialYesPartial
Perfluoroheptanesulfonicacid (PFHPS)PartialYesPartial
AsbestosPartialYesPartial
Coliform Bacteria (indicator)NoYesNo
Gross Alpha Particle ActivityNoNoNo
Langelier Index (pH(s))NoNoNo
MagnesiumNoPartialNo
PotassiumNoPartialNo
SodiumNoPartialNo
Hardness, Total (ASCACO3)NoNoNo
CalciumNoPartialNo
Alkalinity, BicarbonateNoNoNo
pHNoNoNo
pH, FieldNoNoNo
OrthophosphateNoNoNo
Alkalinity, CarbonateNoNoNo

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What is TTHM? Understanding EPA Violation Status Is Chromium-6 Dangerous? Whole-House vs. Under-Sink Filtration Lead and Copper in Drinking Water What is PFAS? Arsenic and Uranium Explained Nitrate and Fluoride Explained Water Hardness, pH, and Turbidity What is Coliform Bacteria?