SONOMA is served by 4 water providers on file with the EPA.
Data current as of July 2026
🔍Straight from EPA
🧪Real Lab Results
📅Updated Quarterly
🏠Local Expertise
Results for SONOMA, CA
4 water providers on file serving this city.
Quick answer: SONOMA's water has no violations on file and no single reading stands out against its peers (4 other providers in this area). It serves roughly 11,725 people, and the full breakdown below reflects everything EPA and California have on record for it.
Lead Summary
Copper Summary
Lithium
PFOA
PFHXA
TTHM
Chloroform
Bromoform
Bromodichloromethane
Dibromochloromethane
Dichloroaceticacid
Trichloroaceticacid
Dibromoaceticacid
Alkalinity, Total
Alkalinity, Bicarbonate
Magnesium
Calcium
Sodium
Hardness, Total (ASCACO3)
TDS
Sulfate
Chloride
Fluoride
Nitrate
Turbidity
Radium-226
Radium-228
pH
Iron
Manganese
Chromium, Hex
Arsenic
Conductivity (at 25°C)
Contaminants found
Metals
Naturally occurring or corrosion-related elements, e.g. lead, arsenic, copper
Lead Summary
Detected: 0 mg/L (ppm)
12/31/2023
Copper Summary
Detected: 1.5 mg/L (ppm)
01/31/1993
Iron
Detected: 82 UG/L (ppb)
9/2/2025
Mostly an aesthetic issue (metallic taste, staining) rather than a health concern at typical levels.
Manganese
Detected: 22 UG/L (ppb)
9/2/2025
Mainly a taste/staining concern at typical levels; long-term neurological research at high chronic exposure is ongoing.
Chromium, Hex
Detected: 0.91 UG/L (ppb)
2/24/2025
Arsenic
Detected: 7.4 UG/L (ppb)
9/23/2025
Occurs naturally in some groundwater. Long-term exposure above the legal limit (10 ppb) has been linked to increased cancer risk and cardiovascular disease.
Disinfection Byproducts
Formed when chlorine used to disinfect water reacts with organic matter
TTHM
Detected: 23 UG/L (ppb)
9/3/2025
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.
Chloroform
Detected: 9.3 UG/L (ppb)
9/3/2025
One of the individual trihalomethane disinfection byproducts, formed when chlorine reacts with organic matter.
Bromoform
Detected: 1.1 UG/L (ppb)
9/3/2025
Bromodichloromethane
Detected: 7 UG/L (ppb)
9/3/2025
Dibromochloromethane
Detected: 5.4 UG/L (ppb)
9/3/2025
Inorganics
Common dissolved minerals and salts, e.g. nitrate, fluoride, chloride
Sulfate
Detected: 5.6 MG/L (ppm)
9/2/2025
Chloride
Detected: 7.4 MG/L (ppm)
9/2/2025
Fluoride
Detected: 0.3 MG/L (ppm)
9/2/2025
Often added deliberately for dental health; can also occur naturally.
Nitrate
Detected: 4.9 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: 6.96 MG/L (ppm)
9/2/2025
Calcium
Detected: 11 MG/L (ppm)
9/2/2025
Sodium
Detected: 21 MG/L (ppm)
9/2/2025
Properties
General water characteristics like pH, hardness, and cloudiness (turbidity)
Hardness, Total (ASCACO3)
Detected: 56.1 MG/L (ppm)
9/2/2025
pH
Detected: 7.83 PH
9/2/2025
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
Lithium
Detected: 29 µg/L (ppb)
1/16/2024
Occurs naturally in some groundwater. Not currently federally regulated in drinking water.
PFOA
Detected: 0.0062 µg/L (ppb)
1/16/2024
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
PFHXA
Detected: 0.0061 µg/L (ppb)
1/16/2024
Calculated Parameters
Values worked out mathematically from other test results, not measured directly
Alkalinity, Bicarbonate
Detected: 93 MG/L (ppm)
9/2/2025
Other
Additional substances tested that don't fit neatly into the categories above
Dichloroaceticacid
Detected: 2.2 UG/L (ppb)
9/3/2025
Trichloroaceticacid
Detected: 1.2 UG/L (ppb)
9/3/2025
Dibromoaceticacid
Detected: 1.6 UG/L (ppb)
9/3/2025
Alkalinity, Total
Detected: 93 MG/L (ppm)
9/2/2025
TDS
Detected: 204 MG/L (ppm)
9/2/2025
Turbidity
Detected: 0.6 NTU
9/2/2025
A measure of water cloudiness from suspended particles.
Radium-226
Detected: 0.173 PCI/L
9/23/2025
Radium-228
Detected: 1.09 PCI/L
6/11/2025
Conductivity (at 25°C)
Detected: 225 UMHO/CM
9/2/2025
Filtration considerations: General system types, not a specific product recommendation.