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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 California Department of Public Health (CDPH) 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.

CDPH Primary and Secondary Standards Maximum Contaminant Levels

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

Contaminant MCL DLR
Inorganic Chemicals
Aluminum 1 0.05
Antimony 0.006 0.006
Antimony
Arsenic 0.010 0.002
Asbestos (MFL = million fibers per liter; for fibers >10 microns long) 7 MFL 0.2 MFL
Barium 1 0.1
Beryllium 0.004 0.001
Cadmium 0.005 0.001
Chromium, Total – OEHHA withdrew the  0.0025-mg/L PHG 0.05 0.01
Chromium-6 – MCL to be established – currently regulated under the total chromium MCL 0.001
Cyanide 0.15 0.1
Fluoride 2 0.1
Mercury (inorganic) 0.002 0.001
Nickel 0.1 0.01
Nitrate (as NO3) 45 2
Nitrite (as N) 1 as N 0.4
Nitrate + Nitrite 10 as N
Perchlorate 0.006 0.004
Perchlorate
Selenium 0.05 0.005
Thallium 0.002 0.001
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
Copper 1.3 0.05
Lead 0.015 0.005
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 practical 15 3
Gross beta particle activity  – OEHHA concluded in 2003 that a PHG was not practical 4 mrem/yr 4
Radium-226 1
Radium-228 1
Radium-226 + Radium-228 5
Strontium-90 8 2
Tritium 20,000 1,000
Uranium 20 1
Organic Chemicals
(a) Volatile Organic Chemicals (VOCs)
Benzene 0.001 0.0005
Carbon tetrachloride 0.0005 0.0005
1,2-Dichlorobenzene 0.6 0.0005
1,4-Dichlorobenzene (p-DCB) 0.005 0.0005
1,1-Dichloroethane (1,1-DCA) 0.005 0.0005
1,2-Dichloroethane (1,2-DCA) 0.0005 0.0005
1,1-Dichloroethylene (1,1-DCE) 0.006 0.0005
cis-1,2-Dichloroethylene 0.006 0.0005
trans-1,2-Dichloroethylene 0.01 0.0005
Dichloromethane (Methylene chloride) 0.005 0.0005
1,2-Dichloropropane 0.005 0.0005
1,3-Dichloropropene 0.0005 0.0005
Ethylbenzene 0.3 0.0005
Methyl tertiary butyl ether (MTBE) 0.013 0.003
Monochlorobenzene 0.07 0.0005
Styrene 0.1 0.0005
1,1,2,2-Tetrachloroethane 0.001 0.0005
Tetrachloroethylene (PCE) 0.005 0.0005
Toluene 0.15 0.0005
1,2,4-Trichlorobenzene 0.005 0.0005
1,1,1-Trichloroethane (1,1,1-TCA) 0.2 0.0005
1,1,2-Trichloroethane (1,1,2-TCA) 0.005 0.0005
Trichloroethylene (TCE) 0.005 0.0005
Trichlorofluoromethane (Freon 11) 0.15 0.005
1,1,2-Trichloro-1,2,2-Trifluoroethane (Freon 113) 1.2 0.01
Vinyl chloride 0.0005 0.0005
Xylenes 1.75 0.0005
(b) Non-Volatile Synthetic Organic Chemicals (SOCs)
Alachlor 0.002 0.001
Atrazine 0.001 0.0005
Bentazon 0.018 0.002
Benzo(a)pyrene 0.0002 0.0001
Carbofuran 0.018 0.005
Chlordane 0.0001 0.0001
Dalapon 0.2 0.01
1,2-Dibromo-3-chloropropane (DBCP) 0.0002 0.00001
2,4-Dichlorophenoxyacetic acid (2,4-D) 0.07 0.01
Di(2-ethylhexyl)adipate 0.4 0.005
Di(2-ethylhexyl)phthalate (DEHP) 0.004 0.003
Dinoseb 0.007 0.002
Diquat 0.02 0.004
Endrin 0.002 0.0001
Endothal 0.1 0.045
Ethylene dibromide (EDB) 0.00005 0.00002
Glyphosate 0.7 0.025
Heptachlor 0.00001 0.00001
Heptachlor epoxide 0.00001 0.00001
Hexachlorobenzene 0.001 0.0005
Hexachlorocyclopentadiene 0.05 0.001
Lindane 0.0002 0.0002
Methoxychlor 0.03 0.01
Molinate 0.02 0.002
Oxamyl 0.05 0.02
Pentachlorophenol 0.001 0.0002
Picloram 0.5 0.001
Polychlorinated biphenyls (PCBs) 0.0005 0.0005
Simazine 0.004 0.001
2,4,5-TP (Silvex) 0.05 0.001
2,3,7,8-TCDD (dioxin) 3×10-8 5×10-9
Thiobencarb 0.07 0.001
Toxaphene 0.003 0.001
Disinfection Byproducts
Total Trihalomethanes 0.080
     Bromodichloromethane 0.0005
     Bromoform 0.0005
     Chloroform 0.0005
     Dibromochloromethane 0.0005
Haloacetic Acids (five) (HAA5) 0.060
     Monochloroacetic Acid 0.002
     Dichloroacetic Adic 0.001
     Trichloroacetic Acid 0.001
     Monobromoacetic Acid 0.001
     Dibromoacetic Acid 0.001
Bromate 0.010 0.005
Chlorite 1.0 0.02
Secondary Standards
Aluminum 0.2 mg/L -
Color 15 Units -
Copper 1.0 mg/L -
Foaming Agents (MBAS) 0.5 mg/L -
Iron 0.3 mg/L -
Manganese 0.05 mg/L -
Methyl-tert-butyl ether (MTBE) 0.005 mg/L -
Odor—Threshold 3 Units -
Silver 0.1 mg/L -
Thiobencarb 0.001 mg/L -
Turbidity 5 Units -
Zinc 5.0 mg/L -
Constituent, Units RecommendedRange Upper Range Short Term Range
Total Dissolved Solids, mg/L 500 1,000 1,500
or
Specific Conductance, μS/cm 900 1,600 2,200
Chloride, mg/L 250 500 600
Sulfate, mg/L 250 500 600
Treatment Technique
Acrylamide TreatmentTechnique
Epichlorohydrin TreatmentTechnique
Microorganisms
Cryptosporidium Log Removal 1
Giardia Lamblia Log Removal 1
Legionella Log Removal 1
Totla Coliforms (Includes E.Coli) 5.00%
Viruses (Enteric) Log Removal 1
HPCs2 n/a
Turbidity Treatment
1. Based on Required Log Removal at Specific Raw Water Quality – but has Specific Microbials Cited
2. Used as a Measaure of Acceptable Disinfectant Residual
Contaminant Notification Level (mg/L)
Boron 1
n-Butylbenzene 0.26
sec-Butylbenzene 0.26
tert-Butylbenzene 0.26
Carbon disulfide 0.16
Chlorate 0.8
2-Chlorotoluene 0.14
4-Chlorotoluene 0.14
Diazinon 0.0012
Dichlorodifluoromethane (Freon 12) 1
1,4-Dioxane 0.001
Ethylene glycol 14
Formaldehyde 0.1
HMX 0.35
Isopropylbenzene 0.77
Manganese 0.5
Methyl isobutyl ketone (MIBK) 0.12
Naphthalene 0.017
N-Nitrosodiethyamine (NDEA) 0.00001
N-Nitrosodimethylamine (NDMA) 0.00001
N-Nitrosodi-n-propylamine (NDPA) 0.00001
Propachlor** 0.09
n-Propylbenzene 0.26
RDX 0.0003
Tertiary butyl alcohol (TBA) 0.012
1,2,3-Trichloropropane (1,2,3-TCP) 0.000005
1,2,4-Trimethylbenzene 0.33
1,3,5-Trimethylbenzene 0.33
2,4,6-Trinitrotoluene (TNT) 0.001
Vanadium 0.05