Serving roughly 198,000 people in Contra Costa County, California.
Data current as of July 2026
🔍Straight from EPA
🧪Real Lab Results
📅Updated Quarterly
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Results for CONTRA COSTA WATER DISTRICT
1 water provider directly on file, serving roughly 198,000 people in Contra Costa County, California.
Quick answer: CONTRA COSTA WATER DISTRICT has no violations on file and no single reading stands out against its peers (179 other providers in this area). It serves roughly 198,000 people, and the full breakdown below reflects everything EPA and California have on record for it.
Lead Summary
Magnesium
Potassium
Sodium
Calcium
Nitrogen-Ammoniaas (N)
Alkalinity, Total
Alkalinity, Bicarbonate
Hardness, Total (ASCACO3)
TDS
Chloride
Sulfate
Fluoride
Nitrate-Nitrite
Nitrate
pH
Odor
Boron, Total
Totalhaloaceticacids (HAA5)
TTHM
Chromium, Hex
Chloroform
Bromoform
Bromodichloromethane
Dibromochloromethane
Dichloroaceticacid
Trichloroaceticacid
Dibromoaceticacid
Cyanide
Copper, Free
Conductivity (at 25°C)
Lead
Monochloroaceticacid
Utility CONTRA COSTA WATER DISTRICTPopulation served 198,000Owner Local government
No violations on file
Contaminants found
Metals
Naturally occurring or corrosion-related elements, e.g. lead, arsenic, copper
Lead Summary
Detected: 0.0031 mg/L (ppm)
12/31/2025
Chromium, Hex
Detected: 0.2 UG/L (ppb)
7/15/2025
Copper, Free
Detected: 20 UG/L (ppb)
7/15/2025
Lead
Detected: 0.7 UG/L (ppb)
6/20/2025
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.
Disinfection Byproducts
Formed when chlorine used to disinfect water reacts with organic matter
Totalhaloaceticacids (HAA5)
Detected: 6.85 UG/L (ppb)
9/15/2025
TTHM
Detected: 18 UG/L (ppb)
9/15/2025
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: 5.8 UG/L (ppb)
9/15/2025
One of the individual trihalomethane disinfection byproducts, formed when chlorine reacts with organic matter.
Bromoform
Detected: 1 UG/L (ppb)
9/15/2025
Bromodichloromethane
Detected: 6.8 UG/L (ppb)
9/15/2025
Dibromochloromethane
Detected: 4.7 UG/L (ppb)
9/15/2025
Inorganics
Common dissolved minerals and salts, e.g. nitrate, fluoride, chloride
Chloride
Detected: 33 MG/L (ppm)
7/15/2025
Sulfate
Detected: 71 MG/L (ppm)
7/15/2025
Fluoride
Detected: 0.68 MG/L (ppm)
7/15/2025
Often added deliberately for dental health; can also occur naturally.
Nitrate-Nitrite
Detected: 0.19 MG/L (ppm)
4/7/2025
Nitrate
Detected: 0.19 MG/L (ppm)
4/7/2025
Commonly from agricultural fertilizer runoff or septic systems. Above the legal limit, it's an immediate concern especially for infants.
Boron, Total
Detected: 82 UG/L (ppb)
7/15/2025
Minerals
Everyday minerals that mainly affect taste and water hardness
Magnesium
Detected: 10.1 MG/L (ppm)
10/15/2025
Potassium
Detected: 2.34 MG/L (ppm)
10/15/2025
Sodium
Detected: 54.6 MG/L (ppm)
10/15/2025
Calcium
Detected: 14.9 MG/L (ppm)
10/15/2025
Properties
General water characteristics like pH, hardness, and cloudiness (turbidity)
Hardness, Total (ASCACO3)
Detected: 82.2 MG/L (ppm)
7/15/2025
pH
Detected: 8.43 PH
7/15/2025
A measure of how acidic or basic the water is (7 is neutral). Affects taste and plumbing, not a direct health measure.
Calculated Parameters
Values worked out mathematically from other test results, not measured directly
Alkalinity, Bicarbonate
Detected: 51.5 MG/L (ppm)
7/15/2025
Other
Additional substances tested that don't fit neatly into the categories above
Nitrogen-Ammoniaas (N)
Detected: 0.48 MG/L (ppm)
7/15/2025
Alkalinity, Total
Detected: 51.5 MG/L (ppm)
7/15/2025
TDS
Detected: 174 MG/L (ppm)
7/15/2025
Odor
Detected: 1 TON
7/15/2025
Dichloroaceticacid
Detected: 4.24 UG/L (ppb)
9/15/2025
Trichloroaceticacid
Detected: 1.18 UG/L (ppb)
9/15/2025
Dibromoaceticacid
Detected: 1.43 UG/L (ppb)
9/15/2025
Cyanide
Detected: 1.4 UG/L (ppb)
7/15/2025
Conductivity (at 25°C)
Detected: 324 UMHO/CM
7/15/2025
Monochloroaceticacid
Detected: 1.7 UG/L (ppb)
9/15/2025
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.