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Water Quality Lookup / California / Monterey County
EPA SDWIS Β· Monterey County, California Β· 672 providers profiled

Monterey County, CA Water Quality Report

Monterey County is served by 672 major public water systems on file with the EPA.

Data current as of July 2026
πŸ”Straight from EPA
πŸ§ͺReal Lab Results
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Results for Monterey County, CA

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

Quick answer: Monterey County has 672 water providers profiled, sorted by population served.

Violations on file

Coliform (TCR)
Older/archived health-based violation
Found at 55 of 672 providers
Nitrate
Older/archived health-based violation
Found at 41 of 672 providers
Commonly from agricultural fertilizer runoff or septic systems. Above the legal limit, it's an immediate concern especially for infants.
Selenium
Older/archived health-based violation
Found at 3 of 672 providers
Surface Water Treatment Rule
Older/archived health-based violation
Found at 3 of 672 providers
Total Haloacetic Acids (HAA5)
Older/archived health-based violation
Found at 1 of 672 providers
Interim Enhanced Surface Water Treatment Rule
Older/archived health-based violation
Found at 1 of 672 providers
Lead And Copper Rule Revisions
Currently open health violation
Found at 42 of 672 providers
Arsenic
Older/archived health-based violation
Found at 7 of 672 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.
Revised Total Coliform Rule
Currently open health violation
Found at 2 of 672 providers
Groundwater Rule
Currently open health violation
Found at 1 of 672 providers

Contaminants found

Metals
Naturally occurring or corrosion-related elements, e.g. lead, arsenic, copper
Lead Summary
Detected: 0.02 mg/L (ppm)
Found at 278 providers
Copper Summary
Detected: 88.4 mg/L (ppm)
Found at 36 providers
Chromium, Hex
Detected: 31 UG/L (ppb)
Found at 96 providers
Arsenic
Detected: 82.6 UG/L (ppb)
Found at 69 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.
Iron
Detected: 6890 UG/L (ppb)
Found at 48 providers
Mostly an aesthetic issue (metallic taste, staining) rather than a health concern at typical levels.
Manganese
Detected: 909 UG/L (ppb)
Found at 42 providers
Mainly a taste/staining concern at typical levels; long-term neurological research at high chronic exposure is ongoing.
Chromium
Detected: 22.1 UG/L (ppb)
Found at 34 providers
Occurs in two forms β€” trivalent (an essential nutrient in trace amounts) and hexavalent (linked to increased cancer risk).
Barium
Detected: 208 UG/L (ppb)
Found at 49 providers
Selenium
Detected: 24 UG/L (ppb)
Found at 32 providers
Copper, Free
Detected: 5150 UG/L (ppb)
Found at 95 providers
Lead
Detected: 71.5 UG/L (ppb)
Found at 65 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.
Combined Uranium
Detected: 16.4 PCI/L
Found at 20 providers
A naturally occurring radioactive metal. Long-term exposure above the legal limit is associated with kidney effects and increased cancer risk.
Zinc
Detected: 14100 UG/L (ppb)
Found at 19 providers
Nickel
Detected: 14.6 UG/L (ppb)
Found at 10 providers
Cadmium
Detected: 2.5 UG/L (ppb)
Found at 7 providers
Aluminum
Detected: 1590 UG/L (ppb)
Found at 6 providers
Vanadium, Total
Detected: 12.3 UG/L (ppb)
Found at 2 providers
Antimony, Total
Detected: 1 UG/L (ppb)
Found at 5 providers
Manganese, Dissolved
Detected: 104 UG/L (ppb)
10/24/2025
Iron, Dissolved
Detected: 1170 UG/L (ppb)
10/24/2025
Lithium, Total
Detected: 15 UG/L (ppb)
Found at 2 providers
Silver
Detected: 1.6 UG/L (ppb)
6/5/2025
Strontium
Detected: 490 UG/L (ppb)
Found at 2 providers
Disinfection Byproducts
Formed when chlorine used to disinfect water reacts with organic matter
TTHM
Detected: 76 UG/L (ppb)
Found at 58 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: 38 UG/L (ppb)
Found at 35 providers
One of the individual trihalomethane disinfection byproducts, formed when chlorine reacts with organic matter.
Bromodichloromethane
Detected: 22 UG/L (ppb)
Found at 50 providers
Dibromochloromethane
Detected: 30 UG/L (ppb)
Found at 64 providers
Bromoform
Detected: 57 UG/L (ppb)
Found at 57 providers
Totalhaloaceticacids (HAA5)
Detected: 113 UG/L (ppb)
Found at 27 providers
Inorganics
Common dissolved minerals and salts, e.g. nitrate, fluoride, chloride
Nitrate
Detected: 96.1 MG/L (ppm)
Found at 220 providers
Commonly from agricultural fertilizer runoff or septic systems. Above the legal limit, it's an immediate concern especially for infants.
Nitrate-Nitrite
Detected: 28.5 MG/L (ppm)
Found at 50 providers
Fluoride
Detected: 2.2 MG/L (ppm)
Found at 59 providers
Often added deliberately for dental health; can also occur naturally.
Chloride
Detected: 771 MG/L (ppm)
Found at 53 providers
Boron, Total
Detected: 2000 UG/L (ppb)
Found at 6 providers
Sulfate
Detected: 417 MG/L (ppm)
Found at 50 providers
Nitrite
Detected: 1.2 MG/L (ppm)
1/8/2025
Minerals
Everyday minerals that mainly affect taste and water hardness
Sodium
Detected: 260 MG/L (ppm)
Found at 51 providers
Magnesium
Detected: 48.5 MG/L (ppm)
Found at 49 providers
Potassium
Detected: 8.5 MG/L (ppm)
Found at 45 providers
Calcium
Detected: 206 MG/L (ppm)
Found at 54 providers
Properties
General water characteristics like pH, hardness, and cloudiness (turbidity)
Gross Alpha Particle Activity
Detected: 19.4 PCI/L
Found at 34 providers
pH
Detected: 8.2 PH
Found at 45 providers
A measure of how acidic or basic the water is (7 is neutral). Affects taste and plumbing, not a direct health measure.
Langelier Index (pH(s))
Detected: 1.32 LANG
Found at 47 providers
Hardness, Total (ASCACO3)
Detected: 661 MG/L (ppm)
Found at 48 providers
pH, Field
Detected: 7.77 PH
Found at 11 providers
Orthophosphate
Detected: 2.9 MG/L (ppm)
Found at 6 providers
PFAS & Emerging Contaminants
Human-made "forever chemicals" and other substances not yet fully regulated
Lithium
Detected: 25.3 Β΅g/L (ppb)
Found at 12 providers
Occurs naturally in some groundwater. Not currently federally regulated in drinking water.
PFPEA
Detected: 0.0092 Β΅g/L (ppb)
8/7/2023
PFHPA
Detected: 0.0036 Β΅g/L (ppb)
8/7/2023
PFHXA
Detected: 0.0093 Β΅g/L (ppb)
8/7/2023
PFOA
Detected: 0.0081 Β΅g/L (ppb)
8/7/2023
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
PFOS
Detected: 0.0073 Β΅g/L (ppb)
8/7/2023
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
PFHXS
Detected: 0.0087 Β΅g/L (ppb)
8/7/2023
PFBS
Detected: 0.0132 Β΅g/L (ppb)
8/7/2023
PFBA
Detected: 0.005 Β΅g/L (ppb)
8/7/2023
VOCs (Volatile Organic Compounds)
Industrial solvents and fuel-related chemicals that evaporate easily
Bromide
Detected: 0.8 MG/L (ppm)
Found at 23 providers
1, 2, 3-Trichloropropane
Detected: 0.118 UG/L (ppb)
Found at 7 providers
Trichloroethylene
Detected: 1.5 UG/L (ppb)
10/2/2025
Petroleum Compounds
Substances associated with fuel or petroleum contamination
Toluene
Detected: 1.1 UG/L (ppb)
3/4/2025
Calculated Parameters
Values worked out mathematically from other test results, not measured directly
Alkalinity, Bicarbonate
Detected: 533 MG/L (ppm)
Found at 50 providers
Alkalinity, Carbonate
Detected: 7.1 MG/L (ppm)
2/13/2025
Other
Additional substances tested that don't fit neatly into the categories above
Conductivity (at 25Β°C)
Detected: 2693 UMHO/CM
Found at 57 providers
Trichloroaceticacid
Detected: 39 UG/L (ppb)
Found at 22 providers
Dibromoaceticacid
Detected: 24 UG/L (ppb)
Found at 50 providers
Dichloroaceticacid
Detected: 57 UG/L (ppb)
Found at 34 providers
Monobromoaceticacid
Detected: 4 UG/L (ppb)
Found at 11 providers
Monochloroaceticacid
Detected: 13 UG/L (ppb)
Found at 10 providers
Bromate
Detected: 1.8 UG/L (ppb)
10/15/2025
TDS
Detected: 1700 MG/L (ppm)
Found at 63 providers
TotalradiumforntncperΒ§64442(B) (3)
Detected: 3.41 PCI/L
7/24/2025
Alkalinity, Total
Detected: 437 MG/L (ppm)
Found at 53 providers
Turbidity
Detected: 110 NTU
Found at 49 providers
A measure of water cloudiness from suspended particles.
Odor
Detected: 3 TON
Found at 11 providers
Adsorbableorganicfluorine
Detected: 3900 NG/L (ppt)
Found at 2 providers
Color
Detected: 75 UNITS
Found at 29 providers
Perchlorate
Detected: 3.8 UG/L (ppb)
Found at 15 providers
Can occur naturally or from industrial/military sources; may interfere with thyroid function at elevated levels.
Radium-228
Detected: 0.745 PCI/L
Found at 14 providers
Combined Radium (-226 & -228)
Detected: 1.29 PCI/L
Found at 5 providers
A naturally occurring radioactive element found in some groundwater.
Aggressive Index
Detected: 12.7 AGGR
Found at 41 providers
Langelier Index (Source Temp.)
Detected: 0.5 LANG
Found at 35 providers
Perfluorohexanoicacid (PFHXA)
Detected: 2.2 NG/L (ppt)
3/5/2025
Carbon, Total
Detected: 1.84 MG/L (ppm)
10/22/2025
Temperature (CENTIGRADE)
Detected: 23.3 C
Found at 11 providers
Silica
Detected: 57 MG/L (ppm)
Found at 9 providers
Radium-226
Detected: 1.29 PCI/L
7/24/2025
Nitrogen-Ammoniaas (N)
Detected: 0.75 MG/L (ppm)
Found at 2 providers
Chlorite
Detected: 0.38 MG/L (ppm)
Found at 2 providers
Foamingagents (SURFACTANTS)
Detected: 0.076 MG/L (ppm)
Found at 2 providers
Gross Beta Particle Activity
Detected: 6.92 PCI/L
9/23/2025
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
1, 2, 3-TrichloropropaneYesYesYes
LeadPartialYesPartial
ArsenicPartialYesPartial
Chromium-6 (Hexavalent)PartialYesPartial
CopperPartialYesPartial
Combined UraniumPartialYesPartial
PFOAPartialYes*Partial
PFOSPartialYes*Partial
NitratePartialYesPartial
Combined RadiumPartialYesPartial
Chromium, HexPartialYesPartial
IronPartialYesPartial
ManganesePartialYesPartial
Conductivity (at 25Β°C)PartialYesPartial
TrichloroaceticacidPartialYesPartial
DibromoaceticacidPartialYesPartial
Nitrate-NitritePartialYesPartial
FluoridePartialYesPartial
ChromiumPartialYesPartial
BariumPartialYesPartial
SeleniumPartialYesPartial
Copper, FreePartialYesPartial
DichloroaceticacidPartialYesPartial
MonobromoaceticacidPartialYesPartial
MonochloroaceticacidPartialYesPartial
BromatePartialYesPartial
TDSPartialYesPartial
ChloridePartialYesPartial
Boron, TotalPartialYesPartial
TotalradiumforntncperΒ§64442(B) (3)PartialYesPartial
Combined UraniumPartialYesPartial
Alkalinity, TotalPartialYesPartial
SulfatePartialYesPartial
OdorPartialYesPartial
ZincPartialYesPartial
AdsorbableorganicfluorinePartialYesPartial
NickelPartialYesPartial
ColorPartialYesPartial
PerchloratePartialYesPartial
Combined Radium (-226 & -228)PartialYesPartial
Aggressive IndexPartialYesPartial
Langelier Index (Source Temp.)PartialYesPartial
Perfluorohexanoicacid (PFHXA)PartialYesPartial
CadmiumPartialYesPartial
Carbon, TotalPartialYesPartial
Temperature (CENTIGRADE)PartialYesPartial
SilicaPartialYesPartial
Radium-226PartialYesPartial
AluminumPartialYesPartial
Nitrogen-Ammoniaas (N)PartialYesPartial
NitritePartialYesPartial
Vanadium, TotalPartialYesPartial
Antimony, TotalPartialYesPartial
ChloritePartialYesPartial
LithiumPartialYes*Partial
PFPEAPartialYes*Partial
PFHPAPartialYes*Partial
PFHXAPartialYes*Partial
PFHXSPartialYes*Partial
PFBSPartialYes*Partial
PFBAPartialYes*Partial
Manganese, DissolvedPartialYesPartial
Iron, DissolvedPartialYesPartial
Lithium, TotalPartialYesPartial
Foamingagents (SURFACTANTS)PartialYesPartial
SilverPartialYesPartial
StrontiumPartialYesPartial
Gross Beta Particle ActivityPartialYesPartial
Coliform Bacteria (indicator)NoYesNo
Gross Alpha Particle ActivityNoNoNo
SodiumNoPartialNo
pHNoNoNo
Langelier Index (pH(s))NoNoNo
MagnesiumNoPartialNo
PotassiumNoPartialNo
CalciumNoPartialNo
Alkalinity, BicarbonateNoNoNo
Hardness, Total (ASCACO3)NoNoNo
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?