Serving roughly 43,821 people in Sonoma County, California.
Data current as of July 2026
🔍Straight from EPA
🧪Real Lab Results
📅Updated Quarterly
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Results for ROHNERT PARK, CITY OF
1 water provider directly on file, serving roughly 43,821 people in Sonoma County, California.
Quick answer: ROHNERT PARK, CITY OF has no violations on file. One reading is worth knowing about: PFHXS was measured at 0.0057µg/L, among the highest of the 756 providers on file in this area. It's the most notable figure in this system's record among its 756 local peers.
Lead Summary
Lithium
6:2 Fts
PFHXS
PFOS
Totalhaloaceticacids (HAA5)
TTHM
Chloroform
Bromoform
Bromodichloromethane
Dibromochloromethane
Dichloroaceticacid
Trichloroaceticacid
Dibromoaceticacid
Copper, Free
Aggressive Index
Magnesium
Sodium
Calcium
Hardness, Total (ASCACO3)
Alkalinity, Total
Alkalinity, Bicarbonate
TDS
Chloride
Sulfate
Nitrate
Combined Uranium
pH
Chromium, Hex
Arsenic
Conductivity (at 25°C)
Utility ROHNERT PARK, CITY OFPopulation served 43,821Owner Local government
Naturally occurring or corrosion-related elements, e.g. lead, arsenic, copper
Lead Summary
Detected: 0 mg/L (ppm)
12/31/2025
Copper, Free
Detected: 67 UG/L (ppb)
8/15/2025
Combined Uranium
Detected: 4 PCI/L
7/8/2025
A naturally occurring radioactive metal. Long-term exposure above the legal limit is associated with kidney effects and increased cancer risk.
Chromium, Hex
Detected: 4.96 UG/L (ppb)
2/12/2025
Arsenic
Detected: 11 UG/L (ppb)
9/16/2025
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
Totalhaloaceticacids (HAA5)
Detected: 6.9 UG/L (ppb)
9/9/2025
TTHM
Detected: 18.65 UG/L (ppb)
9/9/2025
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: 7.53 UG/L (ppb)
9/9/2025
One of the individual trihalomethane disinfection byproducts, formed when chlorine reacts with organic matter.
Bromoform
Detected: 1.14 UG/L (ppb)
9/9/2025
Bromodichloromethane
Detected: 5.55 UG/L (ppb)
9/9/2025
Dibromochloromethane
Detected: 4.43 UG/L (ppb)
9/9/2025
Inorganics
Common dissolved minerals and salts, e.g. nitrate, fluoride, chloride
Chloride
Detected: 18 MG/L (ppm)
9/9/2025
Sulfate
Detected: 25 MG/L (ppm)
9/9/2025
Nitrate
Detected: 0.88 MG/L (ppm)
9/16/2025
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: 31 MG/L (ppm)
9/9/2025
Sodium
Detected: 22 MG/L (ppm)
9/9/2025
Calcium
Detected: 52 MG/L (ppm)
9/9/2025
Properties
General water characteristics like pH, hardness, and cloudiness (turbidity)
Hardness, Total (ASCACO3)
Detected: 257 MG/L (ppm)
9/9/2025
pH
Detected: 7.76 PH
9/9/2025
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: 34 µg/L (ppb)
10/22/2024
Occurs naturally in some groundwater. Not currently federally regulated in drinking water.
6:2 Fts
Detected: 0.0071 µg/L (ppb)
10/22/2024
PFHXS
Detected: 0.0057 µg/L (ppb)
10/16/2024
PFOS
Detected: 0.0045 µg/L (ppb)
10/16/2024
One of two PFAS with an enforceable federal limit (4 ppt) since 2024.
Calculated Parameters
Values worked out mathematically from other test results, not measured directly
Alkalinity, Bicarbonate
Detected: 210 MG/L (ppm)
9/9/2025
Other
Additional substances tested that don't fit neatly into the categories above
Dichloroaceticacid
Detected: 3.4 UG/L (ppb)
9/9/2025
Trichloroaceticacid
Detected: 1.8 UG/L (ppb)
9/9/2025
Dibromoaceticacid
Detected: 1.7 UG/L (ppb)
9/9/2025
Aggressive Index
Detected: 12.32 AGGR
9/9/2025
Alkalinity, Total
Detected: 210 MG/L (ppm)
9/9/2025
TDS
Detected: 350 MG/L (ppm)
9/9/2025
Conductivity (at 25°C)
Detected: 550 UMHO/CM
9/9/2025
Filtration considerations: See the table below for how whole-house carbon, under-sink reverse osmosis, and under-sink carbon systems compare against what's actually on file here. These are general system types, not a specific product recommendation.