EPA SDWIS ยท Merced County, California ยท 237 providers profiled
Merced County, CA Water Quality Report
Merced County is served by 237 major public water systems on file with the EPA.
Data current as of July 2026
๐Straight from EPA
๐งชReal Lab Results
๐ Updated Quarterly
๐ Local Expertise
Results for Merced County, CA
237 water providers on file for this county, sorted by population served.
Quick answer: Merced County has 237 water providers profiled, sorted by population served.
Lead Summary
1, 2, 3-Trichloropropane
1, 2-Dibromo-3-Chloropropane
Chromium, Hex
TTHM
Chloroform
Bromoform
Bromodichloromethane
Dibromochloromethane
Nitrate-Nitrite
Nitrate
Barium
Arsenic
Copper, Free
Perchlorate
Sodium
Adsorbableorganicfluorine
Perfluorobutanesulfonicacid (PFBS)
Perfluoroheptanoicacid (PFHPA)
Perfluoroctanesulfonicacid (PFOS)
Perfluoroctanoicacid (PFOA)
Perfluorobutanoicacid (PFBA)
Perfluoropentanoicacid (PFPEA)
Perfluoropentanesulfonicacid (PFPES)
Perfluoroheptanesulfonicacid (PFHPS)
Perfluorohexanesulfonicacid (PFHxS)
Perfluorohexanoicacid (PFHXA)
Perfluorooctanesulfonicacid6:2fts
Turbidity
Iron
Manganese
Trichloroethylene
Combined Uranium
Gross Alpha Particle Activity
Aggressive Index
Langelier Index (pH(s))
Magnesium
Calcium
Potassium
Alkalinity, Total
Alkalinity, Bicarbonate
Hardness, Total (ASCACO3)
TDS
Chloride
Sulfate
Fluoride
Radium-228
pH
Conductivity (at 25ยฐC)
Lead
Copper Summary
Chromium
Selenium
Dibromoaceticacid
Aluminum
Zinc
Totalhaloaceticacids (HAA5)
Dichloroaceticacid
Trichloroaceticacid
Monobromoaceticacid
Monochloroaceticacid
Carbon, Total
Alkalinity, Carbonate
Color
PFHXA
PFPEA
PFBA
PFBS
6:2 Fts
PFOS
PFHPA
PFOA
Pfpes
PFHXS
Foamingagents (SURFACTANTS)
Lithium
Gross Beta Particle Activity
Tetrachloroethylene
Methyltert-Butylether
Vanadium, Total
Radium-226
Violations on file
Coliform (TCR)
Older/archived health-based violation
Found at 7 of 237 providers
Nitrate
Older/archived health-based violation
Found at 16 of 237 providers
Commonly from agricultural fertilizer runoff or septic systems. Above the legal limit, it's an immediate concern especially for infants.
Lead And Copper Rule Revisions
Currently open health violation
Found at 11 of 237 providers
Revised Total Coliform Rule
Older/archived health-based violation
Found at 2 of 237 providers
TTHM
Older/archived health-based violation
Found at 1 of 237 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.
Arsenic
Older/archived health-based violation
Found at 2 of 237 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.
Combined Uranium
Older/archived health-based violation
Found at 1 of 237 providers
A naturally occurring radioactive metal. Long-term exposure above the legal limit is associated with kidney effects and increased cancer risk.
Contaminants found
Metals
Naturally occurring or corrosion-related elements, e.g. lead, arsenic, copper
Lead Summary
Detected: 0.032 mg/L (ppm)
Found at 85 providers
Chromium, Hex
Detected: 32 UG/L (ppb)
Found at 32 providers
Barium
Detected: 500 UG/L (ppb)
Found at 22 providers
Arsenic
Detected: 62 UG/L (ppb)
Found at 34 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.
Copper, Free
Detected: 2300 UG/L (ppb)
Found at 32 providers
Iron
Detected: 2050 UG/L (ppb)
Found at 11 providers
Mostly an aesthetic issue (metallic taste, staining) rather than a health concern at typical levels.
Manganese
Detected: 360 UG/L (ppb)
Found at 12 providers
Mainly a taste/staining concern at typical levels; long-term neurological research at high chronic exposure is ongoing.
Combined Uranium
Detected: 7.2 PCI/L
Found at 12 providers
A naturally occurring radioactive metal. Long-term exposure above the legal limit is associated with kidney effects and increased cancer risk.
Lead
Detected: 37.4 UG/L (ppb)
Found at 13 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 Summary
Detected: 1.913 mg/L (ppm)
06/30/1994
Chromium
Detected: 29 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).
Selenium
Detected: 5.5 UG/L (ppb)
Found at 5 providers
Aluminum
Detected: 1750 UG/L (ppb)
Found at 4 providers
Zinc
Detected: 67.9 UG/L (ppb)
Found at 3 providers
Vanadium, Total
Detected: 13 UG/L (ppb)
1/21/2025
Disinfection Byproducts
Formed when chlorine used to disinfect water reacts with organic matter
TTHM
Detected: 91.43 UG/L (ppb)
Found at 20 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: 26 UG/L (ppb)
Found at 11 providers
One of the individual trihalomethane disinfection byproducts, formed when chlorine reacts with organic matter.
Bromoform
Detected: 60.04 UG/L (ppb)
Found at 17 providers
Bromodichloromethane
Detected: 20.5 UG/L (ppb)
Found at 9 providers
Dibromochloromethane
Detected: 36.9 UG/L (ppb)
Found at 15 providers
Totalhaloaceticacids (HAA5)
Detected: 37.8 UG/L (ppb)
Found at 5 providers
Inorganics
Common dissolved minerals and salts, e.g. nitrate, fluoride, chloride
Nitrate-Nitrite
Detected: 30 MG/L (ppm)
Found at 18 providers
Nitrate
Detected: 28.6 MG/L (ppm)
Found at 80 providers
Commonly from agricultural fertilizer runoff or septic systems. Above the legal limit, it's an immediate concern especially for infants.
Chloride
Detected: 115 MG/L (ppm)
Found at 9 providers
Sulfate
Detected: 50 MG/L (ppm)
Found at 9 providers
Fluoride
Detected: 0.2 MG/L (ppm)
Found at 15 providers
Often added deliberately for dental health; can also occur naturally.
Minerals
Everyday minerals that mainly affect taste and water hardness
Sodium
Detected: 89 MG/L (ppm)
Found at 12 providers
Magnesium
Detected: 24 MG/L (ppm)
Found at 11 providers
Calcium
Detected: 55 MG/L (ppm)
Found at 11 providers
Potassium
Detected: 10 MG/L (ppm)
Found at 7 providers
Properties
General water characteristics like pH, hardness, and cloudiness (turbidity)
Gross Alpha Particle Activity
Detected: 15.9 PCI/L
Found at 23 providers
Langelier Index (pH(s))
Detected: 0.44 LANG
Found at 5 providers
Hardness, Total (ASCACO3)
Detected: 220 MG/L (ppm)
Found at 9 providers
pH
Detected: 8 PH
Found at 10 providers
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
PFHXA
Detected: 0.0037 ยตg/L (ppb)
Found at 2 providers
PFPEA
Detected: 0.0048 ยตg/L (ppb)
5/7/2024
PFBA
Detected: 0.008 ยตg/L (ppb)
5/7/2024
PFBS
Detected: 0.0078 ยตg/L (ppb)
Found at 2 providers
6:2 Fts
Detected: 0.013 ยตg/L (ppb)
5/7/2024
PFOS
Detected: 0.045 ยตg/L (ppb)
Found at 5 providers
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
PFHPA
Detected: 0.012 ยตg/L (ppb)
5/7/2024
PFOA
Detected: 0.033 ยตg/L (ppb)
Found at 2 providers
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
Pfpes
Detected: 0.0082 ยตg/L (ppb)
5/7/2024
PFHXS
Detected: 0.059 ยตg/L (ppb)
Found at 4 providers
Lithium
Detected: 21 ยตg/L (ppb)
Found at 2 providers
Occurs naturally in some groundwater. Not currently federally regulated in drinking water.
VOCs (Volatile Organic Compounds)
Industrial solvents and fuel-related chemicals that evaporate easily
1, 2, 3-Trichloropropane
Detected: 0.47 UG/L (ppb)
Found at 21 providers
Trichloroethylene
Detected: 1.7 UG/L (ppb)
10/21/2025
Tetrachloroethylene
Detected: 0.71 UG/L (ppb)
Found at 2 providers
Calculated Parameters
Values worked out mathematically from other test results, not measured directly
Alkalinity, Bicarbonate
Detected: 240 MG/L (ppm)
Found at 12 providers
Alkalinity, Carbonate
Detected: 10 MG/L (ppm)
Found at 2 providers
Other
Additional substances tested that don't fit neatly into the categories above
1, 2-Dibromo-3-Chloropropane
Detected: 0.13 UG/L (ppb)
Found at 10 providers
Perchlorate
Detected: 15 UG/L (ppb)
Found at 4 providers
Can occur naturally or from industrial/military sources; may interfere with thyroid function at elevated levels.
Adsorbableorganicfluorine
Detected: 980 NG/L (ppt)
Found at 3 providers
Perfluorobutanesulfonicacid (PFBS)
Detected: 29 NG/L (ppt)
Found at 3 providers
Perfluoroheptanoicacid (PFHPA)
Detected: 23 NG/L (ppt)
Found at 2 providers
Perfluoroctanesulfonicacid (PFOS)
Detected: 87 NG/L (ppt)
Found at 6 providers
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
Perfluoroctanoicacid (PFOA)
Detected: 75 NG/L (ppt)
Found at 4 providers
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
Perfluorobutanoicacid (PFBA)
Detected: 18 NG/L (ppt)
Found at 3 providers
Perfluoropentanoicacid (PFPEA)
Detected: 61 NG/L (ppt)
Found at 3 providers
Perfluoropentanesulfonicacid (PFPES)
Detected: 24 NG/L (ppt)
Found at 3 providers
Perfluoroheptanesulfonicacid (PFHPS)
Detected: 4.8 NG/L (ppt)
8/26/2025
Perfluorohexanesulfonicacid (PFHxS)
Detected: 140 NG/L (ppt)
Found at 5 providers
Perfluorohexanoicacid (PFHXA)
Detected: 87 NG/L (ppt)
Found at 4 providers
Perfluorooctanesulfonicacid6:2fts
Detected: 31 NG/L (ppt)
Found at 2 providers
Turbidity
Detected: 8.9 NTU
Found at 6 providers
A measure of water cloudiness from suspended particles.
Aggressive Index
Detected: 12.5 AGGR
Found at 5 providers
Alkalinity, Total
Detected: 240 MG/L (ppm)
Found at 12 providers
TDS
Detected: 940 MG/L (ppm)
Found at 11 providers
Radium-228
Detected: 0.796 PCI/L
Found at 3 providers
Conductivity (at 25ยฐC)
Detected: 1260 UMHO/CM
Found at 8 providers
Dibromoaceticacid
Detected: 6.3 UG/L (ppb)
Found at 7 providers
Dichloroaceticacid
Detected: 16.7 UG/L (ppb)
Found at 4 providers
Trichloroaceticacid
Detected: 16 UG/L (ppb)
Found at 5 providers
Monobromoaceticacid
Detected: 3 UG/L (ppb)
Found at 3 providers
Monochloroaceticacid
Detected: 2.1 UG/L (ppb)
10/1/2025
Carbon, Total
Detected: 5.8 MG/L (ppm)
Found at 4 providers
Color
Detected: 20 UNITS
Found at 3 providers
Foamingagents (SURFACTANTS)
Detected: 0.088 MG/L (ppm)
Found at 3 providers
Gross Beta Particle Activity
Detected: 2.9 PCI/L
8/27/2025
Methyltert-Butylether
Detected: 5.6 UG/L (ppb)
8/6/2025
Radium-226
Detected: 0.43 PCI/L
8/26/2025
Filtration considerations: General system types, not a specific product recommendation.