Serving roughly 5,463 people in Tuolumne County, California.
Data current as of July 2026
🔍Straight from EPA
🧪Real Lab Results
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Results for TUD - COLUMBIA WATER SYSTEM
1 water provider directly on file, serving roughly 5,463 people in Tuolumne County, California.
Quick answer: TUD - COLUMBIA WATER SYSTEM has no violations on file. One reading is worth knowing about: pH was measured at 7.9PH, among the highest of the 274 providers on file in this area. It's the most notable figure in this system's record among its 274 local peers.
Lead Summary
Totalhaloaceticacids (HAA5)
TTHM
Chloroform
Dichloroaceticacid
Trichloroaceticacid
Bromodichloromethane
Monochloroaceticacid
Aggressive Index
Langelier Index (pH(s))
Sodium
Alkalinity, Total
Alkalinity, Bicarbonate
Magnesium
Calcium
Hardness, Total (ASCACO3)
TDS
Turbidity
pH
Iron
Manganese
Copper, Free
Conductivity (at 25°C)
Color
Foamingagents (SURFACTANTS)
Utility TUD - COLUMBIA WATER SYSTEMPopulation served 5,463Owner Local government
No violations on file
Contaminants found
Metals
Naturally occurring or corrosion-related elements, e.g. lead, arsenic, copper
Lead Summary
Detected: 0.0047 mg/L (ppm)
12/31/2023
Iron
Detected: 330 UG/L (ppb)
8/5/2025
Mostly an aesthetic issue (metallic taste, staining) rather than a health concern at typical levels.
Manganese
Detected: 14 UG/L (ppb)
8/5/2025
Mainly a taste/staining concern at typical levels; long-term neurological research at high chronic exposure is ongoing.
Copper, Free
Detected: 14 UG/L (ppb)
8/5/2025
Disinfection Byproducts
Formed when chlorine used to disinfect water reacts with organic matter
Totalhaloaceticacids (HAA5)
Detected: 57 UG/L (ppb)
10/7/2025
TTHM
Detected: 22 UG/L (ppb)
10/7/2025
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: 22 UG/L (ppb)
10/7/2025
One of the individual trihalomethane disinfection byproducts, formed when chlorine reacts with organic matter.
Bromodichloromethane
Detected: 1.4 UG/L (ppb)
10/7/2025
Minerals
Everyday minerals that mainly affect taste and water hardness
Sodium
Detected: 1.4 MG/L (ppm)
8/5/2025
Magnesium
Detected: 0.87 MG/L (ppm)
8/5/2025
Calcium
Detected: 2.9 MG/L (ppm)
8/5/2025
Properties
General water characteristics like pH, hardness, and cloudiness (turbidity)
Langelier Index (pH(s))
Detected: -1.9 LANG
8/5/2025
Hardness, Total (ASCACO3)
Detected: 11 MG/L (ppm)
8/5/2025
pH
Detected: 7.9 PH
8/5/2025
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: 19 MG/L (ppm)
8/5/2025
Other
Additional substances tested that don't fit neatly into the categories above
Dichloroaceticacid
Detected: 26 UG/L (ppb)
10/7/2025
Trichloroaceticacid
Detected: 29 UG/L (ppb)
10/7/2025
Monochloroaceticacid
Detected: 2.2 UG/L (ppb)
10/7/2025
Aggressive Index
Detected: 10 AGGR
8/5/2025
Alkalinity, Total
Detected: 19 MG/L (ppm)
8/5/2025
TDS
Detected: 21 MG/L (ppm)
8/5/2025
Turbidity
Detected: 2.1 NTU
8/5/2025
A measure of water cloudiness from suspended particles.
Conductivity (at 25°C)
Detected: 29 UMHO/CM
8/5/2025
Color
Detected: 20 UNITS
8/5/2025
Foamingagents (SURFACTANTS)
Detected: 0.078 MG/L (ppm)
1/27/2025
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.