SAN LUIS OBISPO WATER DEPARTMENT Water Quality Report
Serving roughly 47,788 people in San Luis Obispo County, California.
Data current as of July 2026
🔍Straight from EPA
🧪Real Lab Results
📅Updated Quarterly
🏠Local Expertise
Results for SAN LUIS OBISPO WATER DEPARTMENT
1 water provider directly on file, serving roughly 47,788 people in San Luis Obispo County, California.
Quick answer: SAN LUIS OBISPO WATER DEPARTMENT has no violations on file. One reading is worth knowing about: Color was measured at 22UNITS, among the highest of the 252 providers on file in this area. It's the most notable figure in this system's record among its 252 local peers.
Lead Summary
Lithium
Totalhaloaceticacids (HAA5)
TTHM
Chloroform
Bromodichloromethane
Dibromochloromethane
Dichloroaceticacid
Trichloroaceticacid
Dibromoaceticacid
Bromoform
Monochloroaceticacid
Copper, Free
Aggressive Index
Langelier Index (pH(s))
Magnesium
Potassium
Sodium
Hardness, Total (ASCACO3)
Calcium
Alkalinity, Total
Alkalinity, Bicarbonate
Carbon, Total
TDS
Sulfate
Chloride
Fluoride
Turbidity
Combined Uranium
Gross Alpha Particle Activity
pH, Field
Vanadium, Total
Iron
Manganese
Arsenic
Conductivity (at 25°C)
Color
Aluminum
Utility SAN LUIS OBISPO WATER DEPARTMENTPopulation served 47,788Owner Local government
No violations on file
Contaminants found
Metals
Naturally occurring or corrosion-related elements, e.g. lead, arsenic, copper
Lead Summary
Detected: 0 mg/L (ppm)
12/31/2025
Copper, Free
Detected: 88 UG/L (ppb)
9/25/2025
Combined Uranium
Detected: 6.93 PCI/L
9/9/2025
A naturally occurring radioactive metal. Long-term exposure above the legal limit is associated with kidney effects and increased cancer risk.
Vanadium, Total
Detected: 4 UG/L (ppb)
9/9/2025
Iron
Detected: 80 UG/L (ppb)
9/9/2025
Mostly an aesthetic issue (metallic taste, staining) rather than a health concern at typical levels.
Manganese
Detected: 340 UG/L (ppb)
9/9/2025
Mainly a taste/staining concern at typical levels; long-term neurological research at high chronic exposure is ongoing.
Arsenic
Detected: 2 UG/L (ppb)
9/9/2025
Occurs naturally in some groundwater. Long-term exposure above the legal limit (10 ppb) has been linked to increased cancer risk and cardiovascular disease.
Aluminum
Detected: 130 UG/L (ppb)
10/2/2025
Disinfection Byproducts
Formed when chlorine used to disinfect water reacts with organic matter
Totalhaloaceticacids (HAA5)
Detected: 33 UG/L (ppb)
8/12/2025
TTHM
Detected: 23 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: 11.4 UG/L (ppb)
9/9/2025
One of the individual trihalomethane disinfection byproducts, formed when chlorine reacts with organic matter.
Bromodichloromethane
Detected: 7.4 UG/L (ppb)
9/9/2025
Dibromochloromethane
Detected: 4.6 UG/L (ppb)
9/9/2025
Bromoform
Detected: 1 UG/L (ppb)
2/19/2025
Inorganics
Common dissolved minerals and salts, e.g. nitrate, fluoride, chloride
Sulfate
Detected: 105 MG/L (ppm)
9/9/2025
Chloride
Detected: 18 MG/L (ppm)
9/9/2025
Fluoride
Detected: 0.6 MG/L (ppm)
10/2/2025
Often added deliberately for dental health; can also occur naturally.
Minerals
Everyday minerals that mainly affect taste and water hardness
Magnesium
Detected: 25 MG/L (ppm)
9/9/2025
Potassium
Detected: 2 MG/L (ppm)
9/9/2025
Sodium
Detected: 27 MG/L (ppm)
9/9/2025
Calcium
Detected: 44 MG/L (ppm)
9/9/2025
Properties
General water characteristics like pH, hardness, and cloudiness (turbidity)
Langelier Index (pH(s))
Detected: 0.4 LANG
9/9/2025
Hardness, Total (ASCACO3)
Detected: 213 MG/L (ppm)
9/9/2025
Gross Alpha Particle Activity
Detected: 4.93 PCI/L
9/9/2025
pH, Field
Detected: 7.96 PH
9/9/2025
PFAS & Emerging Contaminants
Human-made "forever chemicals" and other substances not yet fully regulated
Lithium
Detected: 10 µg/L (ppb)
6/7/2023
Occurs naturally in some groundwater. Not currently federally regulated in drinking water.
Calculated Parameters
Values worked out mathematically from other test results, not measured directly
Alkalinity, Bicarbonate
Detected: 180 MG/L (ppm)
9/9/2025
Other
Additional substances tested that don't fit neatly into the categories above
Dichloroaceticacid
Detected: 16 UG/L (ppb)
8/12/2025
Trichloroaceticacid
Detected: 11 UG/L (ppb)
8/12/2025
Dibromoaceticacid
Detected: 2 UG/L (ppb)
8/12/2025
Monochloroaceticacid
Detected: 4 UG/L (ppb)
8/12/2025
Aggressive Index
Detected: 12.2 AGGR
9/9/2025
Alkalinity, Total
Detected: 150 MG/L (ppm)
9/9/2025
Carbon, Total
Detected: 3.2 MG/L (ppm)
10/2/2025
TDS
Detected: 340 MG/L (ppm)
9/9/2025
Turbidity
Detected: 2.3 NTU
9/9/2025
A measure of water cloudiness from suspended particles.
Conductivity (at 25°C)
Detected: 533 UMHO/CM
9/9/2025
Color
Detected: 22 UNITS
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.