Potential Contaminants

Every year, Cal Water’s Water Quality Lab performs hundreds of thousands of tests to monitor the quality of our water. If any contaminants are found, they are listed in the annual water quality report. However, most of the contaminants we test for are not found, so they are not listed in the water quality report.

The below table lists all of the contaminants that the Division of Drinking Water (DDW) requires Cal Water to test for, along with their maximum containment level (MCL) and detection limit for purposes of reporting (DLR). If you have any questions about this table or about the quality of your water, please contact your local Customer Center.

DDW Primary and Secondary Standards Maximum Contaminant Levels

Units are in milligrams per liter (mg/L), unless otherwise noted

ContaminantMCLDLR
Inorganic Chemicals
Aluminum10.05
Antimony0.0060.006
Antimony
Arsenic0.0100.002
Asbestos (MFL = million fibers per liter; for fibers >10 microns long)7 MFL0.2 MFL
Barium10.1
Beryllium0.0040.001
Cadmium0.0050.001
Chromium, Total – OEHHA withdrew the 0.0025-mg/L PHG0.050.01
Chromium-6 – MCL to be established – currently regulated under the total chromium MCL0.001
Cyanide0.150.1
Fluoride20.1
Mercury (inorganic)0.0020.001
Nickel0.10.01
Nitrate (as NO3)452
Nitrite (as N)1 as N0.4
Nitrate + Nitrite10 as N
Perchlorate0.0060.004
Perchlorate
Selenium0.050.005
Thallium0.0020.001
Copper and Lead
Values referred to as MCLs for lead and copper are not actually MCLs; instead, they are called “Action Levels” under the lead and copper rule
Copper1.30.05
Lead0.0150.005
Radionuclides
[units are picocuries per liter (pCi/L), unless otherwise stated; n/a = not applicable]
Gross alpha particle activity – OEHHA concluded in 2003 that a PHG was not practical153
Gross beta particle activity – OEHHA concluded in 2003 that a PHG was not practical4 mrem/yr4
Radium-2261
Radium-2281
Radium-226 + Radium-2285
Strontium-9082
Tritium20,0001,000
Uranium201
Organic Chemicals
(a) Volatile Organic Chemicals (VOCs)
Benzene0.0010.0005
Carbon tetrachloride0.00050.0005
1,2-Dichlorobenzene0.60.0005
1,4-Dichlorobenzene (p-DCB)0.0050.0005
1,1-Dichloroethane (1,1-DCA)0.0050.0005
1,2-Dichloroethane (1,2-DCA)0.00050.0005
1,1-Dichloroethylene (1,1-DCE)0.0060.0005
cis-1,2-Dichloroethylene0.0060.0005
trans-1,2-Dichloroethylene0.010.0005
Dichloromethane (Methylene chloride)0.0050.0005
1,2-Dichloropropane0.0050.0005
1,3-Dichloropropene0.00050.0005
Ethylbenzene0.30.0005
Methyl tertiary butyl ether (MTBE)0.0130.003
Monochlorobenzene0.070.0005
Styrene0.10.0005
1,1,2,2-Tetrachloroethane0.0010.0005
Tetrachloroethylene (PCE)0.0050.0005
Toluene0.150.0005
1,2,4-Trichlorobenzene0.0050.0005
1,1,1-Trichloroethane (1,1,1-TCA)0.20.0005
1,1,2-Trichloroethane (1,1,2-TCA)0.0050.0005
Trichloroethylene (TCE)0.0050.0005
Trichlorofluoromethane (Freon 11)0.150.005
1,1,2-Trichloro-1,2,2-Trifluoroethane (Freon 113)1.20.01
Vinyl chloride0.00050.0005
Xylenes1.750.0005
(b) Non-Volatile Synthetic Organic Chemicals (SOCs)
Alachlor0.0020.001
Atrazine0.0010.0005
Bentazon0.0180.002
Benzo(a)pyrene0.00020.0001
Carbofuran0.0180.005
Chlordane0.00010.0001
Dalapon0.20.01
1,2-Dibromo-3-chloropropane (DBCP)0.00020.00001
2,4-Dichlorophenoxyacetic acid (2,4-D)0.070.01
Di(2-ethylhexyl)adipate0.40.005
Di(2-ethylhexyl)phthalate (DEHP)0.0040.003
Dinoseb0.0070.002
Diquat0.020.004
Endrin0.0020.0001
Endothal0.10.045
Ethylene dibromide (EDB)0.000050.00002
Glyphosate0.70.025
Heptachlor0.000010.00001
Heptachlor epoxide0.000010.00001
Hexachlorobenzene0.0010.0005
Hexachlorocyclopentadiene0.050.001
Lindane0.00020.0002
Methoxychlor0.030.01
Molinate0.020.002
Oxamyl0.050.02
Pentachlorophenol0.0010.0002
Picloram0.50.001
Polychlorinated biphenyls (PCBs)0.00050.0005
Simazine0.0040.001
2,4,5-TP (Silvex)0.050.001
2,3,7,8-TCDD (dioxin)3×10-85×10-9
Thiobencarb0.070.001
Toxaphene0.0030.001
Disinfection Byproducts
Total Trihalomethanes0.080
Bromodichloromethane0.0005
Bromoform0.0005
Chloroform0.0005
Dibromochloromethane0.0005
Haloacetic Acids (five) (HAA5)0.060
Monochloroacetic Acid0.002
Dichloroacetic Adic0.001
Trichloroacetic Acid0.001
Monobromoacetic Acid0.001
Dibromoacetic Acid0.001
Bromate0.0100.005
Chlorite1.00.02
Secondary Standards
Aluminum0.2 mg/L
Color15 Units
Copper1.0 mg/L
Foaming Agents (MBAS)0.5 mg/L
Iron0.3 mg/L
Manganese0.05 mg/L
Methyl-tert-butyl ether (MTBE)0.005 mg/L
Odor—Threshold3 Units
Silver0.1 mg/L
Thiobencarb0.001 mg/L
Turbidity5 Units
Zinc5.0 mg/L
Constituent, UnitsRecommended RangeUpper RangeShort Term Range
Total Dissolved Solids, mg/L5001,0001,500
or
Specific Conductance, μS/cm9001,6002,200
Chloride, mg/L250500600
Sulfate, mg/L250500600
Treatment Technique
AcrylamideTreatment Technique
EpichlorohydrinTreatment Technique
Microorganisms
CryptosporidiumLog Removal 1
Giardia LambliaLog Removal 1
LegionellaLog Removal 1
Totla Coliforms (Includes E.Coli)5.00%
Viruses (Enteric)Log Removal 1
HPCs2n/a
TurbidityTreatment
1. Based on Required Log Removal at Specific Raw Water Quality – but has Specific Microbials Cited
2. Used as a Measure of Acceptable Disinfectant Residual
ContaminantNotification Level (mg/L)
Boron1
n-Butylbenzene0.26
sec-Butylbenzene0.26
tert-Butylbenzene0.26
Carbon disulfide0.16
Chlorate0.8
2-Chlorotoluene0.14
4-Chlorotoluene0.14
Diazinon0.0012
Dichlorodifluoromethane (Freon 12)1
1,4-Dioxane0.001
Ethylene glycol14
Formaldehyde0.1
HMX0.35
Isopropylbenzene0.77
Manganese0.5
Methyl isobutyl ketone (MIBK)0.12
Naphthalene0.017
N-Nitrosodiethyamine (NDEA)0.00001
N-Nitrosodimethylamine (NDMA)0.00001
N-Nitrosodi-n-propylamine (NDPA)0.00001
Propachlor**0.09
n-Propylbenzene0.26
RDX0.0003
Tertiary butyl alcohol (TBA)0.012
1,2,3-Trichloropropane (1,2,3-TCP)0.000005
1,2,4-Trimethylbenzene0.33
1,3,5-Trimethylbenzene0.33
2,4,6-Trinitrotoluene (TNT)0.001
Vanadium0.05