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
| 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 | Recommended Range | 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 | Treatment Technique | ||
| Epichlorohydrin | Treatment Technique | ||
| 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 Measure 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 | ||