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Water Quality Lookup / California / San Luis Obispo County / CAYUCOS
EPA SDWIS · San Luis Obispo County, California

Is CAYUCOS, CA Tap Water Safe?

CAYUCOS is served by 9 water providers on file with the EPA.

Data current as of July 2026
🔍Straight from EPA
🧪Real Lab Results
📅Updated Quarterly
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Results for CAYUCOS, CA

9 water providers on file serving this city.

Quick answer: CAYUCOS's water has no violations on file and no single reading stands out against its peers (9 other providers in this area). It serves roughly 362 people, and the full breakdown below reflects everything EPA and California have on record for it.

Contaminants found

Metals
Naturally occurring or corrosion-related elements, e.g. lead, arsenic, copper
Nickel
Detected: 6.5 UG/L (ppb)
4/24/2025
Barium
Detected: 91 UG/L (ppb)
Found at 2 providers
Selenium
Detected: 3.1 UG/L (ppb)
Found at 2 providers
Lead Summary
Detected: 0 mg/L (ppm)
Found at 2 providers
Copper, Free
Detected: 580 UG/L (ppb)
Found at 2 providers
Manganese
Detected: 10 UG/L (ppb)
7/16/2025
Mainly a taste/staining concern at typical levels; long-term neurological research at high chronic exposure is ongoing.
Chromium, Hex
Detected: 2 UG/L (ppb)
Found at 2 providers
Zinc
Detected: 110 UG/L (ppb)
7/16/2025
Disinfection Byproducts
Formed when chlorine used to disinfect water reacts with organic matter
Totalhaloaceticacids (HAA5)
Detected: 12 UG/L (ppb)
8/12/2025
TTHM
Detected: 51 UG/L (ppb)
Found at 2 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: 8.3 UG/L (ppb)
8/12/2025
One of the individual trihalomethane disinfection byproducts, formed when chlorine reacts with organic matter.
Bromoform
Detected: 7.5 UG/L (ppb)
Found at 2 providers
Bromodichloromethane
Detected: 18 UG/L (ppb)
8/12/2025
Dibromochloromethane
Detected: 18 UG/L (ppb)
Found at 2 providers
Inorganics
Common dissolved minerals and salts, e.g. nitrate, fluoride, chloride
Fluoride
Detected: 0.26 MG/L (ppm)
Found at 2 providers
Often added deliberately for dental health; can also occur naturally.
Chloride
Detected: 30 MG/L (ppm)
7/16/2025
Sulfate
Detected: 94 MG/L (ppm)
7/16/2025
Nitrate-Nitrite
Detected: 1.9 MG/L (ppm)
10/7/2025
Nitrate
Detected: 4.5 MG/L (ppm)
Found at 3 providers
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: 43 MG/L (ppm)
7/16/2025
Sodium
Detected: 39 MG/L (ppm)
7/16/2025
Calcium
Detected: 60 MG/L (ppm)
7/16/2025
Properties
General water characteristics like pH, hardness, and cloudiness (turbidity)
Langelier Index (pH(s))
Detected: 0.56 LANG
7/16/2025
Hardness, Total (ASCACO3)
Detected: 330 MG/L (ppm)
7/16/2025
pH
Detected: 8 PH
7/16/2025
A measure of how acidic or basic the water is (7 is neutral). Affects taste and plumbing, not a direct health measure.
Gross Alpha Particle Activity
Detected: 1.37 PCI/L
8/14/2025
Calculated Parameters
Values worked out mathematically from other test results, not measured directly
Alkalinity, Bicarbonate
Detected: 280 MG/L (ppm)
7/16/2025
Other
Additional substances tested that don't fit neatly into the categories above
Bromate
Detected: 2.3 UG/L (ppb)
8/11/2025
Conductivity (at 25°C)
Detected: 1400 UMHO/CM
Found at 2 providers
Dichloroaceticacid
Detected: 4.4 UG/L (ppb)
8/12/2025
Trichloroaceticacid
Detected: 1.7 UG/L (ppb)
8/12/2025
Dibromoaceticacid
Detected: 6 UG/L (ppb)
Found at 2 providers
Aggressive Index
Detected: 12.6 AGGR
7/16/2025
Alkalinity, Total
Detected: 280 MG/L (ppm)
7/16/2025
TDS
Detected: 510 MG/L (ppm)
7/16/2025
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
LeadPartialYesPartial
ArsenicPartialYesPartial
Chromium-6 (Hexavalent)PartialYesPartial
CopperPartialYesPartial
Combined UraniumPartialYesPartial
PFOAPartialYes*Partial
PFOSPartialYes*Partial
NitratePartialYesPartial
Combined RadiumPartialYesPartial
BromatePartialYesPartial
FluoridePartialYesPartial
NickelPartialYesPartial
BariumPartialYesPartial
SeleniumPartialYesPartial
Conductivity (at 25°C)PartialYesPartial
DichloroaceticacidPartialYesPartial
TrichloroaceticacidPartialYesPartial
DibromoaceticacidPartialYesPartial
Copper, FreePartialYesPartial
Aggressive IndexPartialYesPartial
Alkalinity, TotalPartialYesPartial
TDSPartialYesPartial
ChloridePartialYesPartial
SulfatePartialYesPartial
Nitrate-NitritePartialYesPartial
ManganesePartialYesPartial
Chromium, HexPartialYesPartial
ZincPartialYesPartial
Coliform Bacteria (indicator)NoYesNo
Langelier Index (pH(s))NoNoNo
MagnesiumNoPartialNo
SodiumNoPartialNo
CalciumNoPartialNo
Alkalinity, BicarbonateNoNoNo
Hardness, Total (ASCACO3)NoNoNo
pHNoNoNo
Gross Alpha Particle ActivityNoNoNo

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Learn more
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?
WHATSINMYWATER.CO · DATA FROM EPA & STATE GOVERNMENT SOURCES