The Power of Information

National Drinking Water Database


California Water Service - Stockton - San Jose, CA


Serves 155,670 people - Test data available: 2004-2009

This drinking water quality report shows results of tests conducted by the water utility and provided to the Environmental Working Group (EWG) by the California Department of Public Health. It is part of EWG's national database that includes 47,667 drinking water utilities and 20 million test results. Water utilities nationwide detected more than 300 pollutants between 2004 and 2009. More than half of these chemicals are unregulated, legal in any amount. Despite this widespread contamination, the federal government invests few resources to protecting rivers, reservoirs, and groundwater from pollution in the first place. The information below summarizes test results for this utility and lists potential health concerns.

 
This Drinking Water System
National Average
Exceed Health GuidelinesTests showing chemicals at concentrations above health guidelines established by federal and state health agencies. These guidelines are typically set at a levels that pose no significant health risk.
17 chemicals
4
Health Standard ExceedencesChemicals detected at concentrations above the legal limit, the Maximum Contaminant Level (MCLs) established by the U.S. EPA. Most MCLs are based on annual averages, so exceeding the MCL for one test does not necessarily indicate that the system is out of compliance.
3 chemicals
0.5
Pollutants FoundThe total number of contaminants detected since 2004, according to data provided by the state water agency.
34 chemicals
8
Tests ConductedThe total number of number of water quality tests conducted by water utilities and recorded in data provided by the state water agency.
18,049 tests
420

Contaminants Exceeding Health Guidelines

ContaminantAverage/
Maximum
Result
Health Limit
Exceeded
Legal Limit
Exceeded

Testing History

-Tested      -Detected      -Over Health Guidelines      -Over Legal Limit*
Arsenic (total)Arsenic contaminates drinking water due to mining runoff, erosion of natural deposits, emissions from glass and electronics processing and the use of arsenical compounds as wood preservatives and pesticides.12.13 ppb
25 ppb
Yes
MCLGA non-enforceable health goal that is set at a level at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Source: U.S. Environmental Protection Agency.: 0 ppb
Yes
10 ppb
ManganeseManganese is a naturally occurring element released from mineral deposits as well as industrial use.51.34 ppb
163.25 ppb
Yes
50 ppb
Yes
50 ppb
NitrateNitrate enters drinking water sources from fertilizer runoff, leaching septic tanks, and erosion of natural deposits; it is also emitted by chemical, petrochemical and metal-finishing industries.1.36 ppm
14 ppm
Yes
10 ppm
Yes
10 ppm
TrichloroethyleneTrichloroethylene is used to remove grease from fabricated metal parts and in the production of some textiles; this pollutant comes from metal degreasing sites, metal finishing and rubber processing industries.0.15 ppb
2.47 ppb
Yes
MCLGA non-enforceable health goal that is set at a level at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Source: U.S. Environmental Protection Agency.: 0 ppb
No
5 ppb
TetrachloroethyleneTetrachloroethylene (perc) is a common soil and groundwater contaminant used in dry cleaning and as a solvent in automotive and metalworking factories and other industries.0.07 ppb
1.52 ppb
Yes
MCLGA non-enforceable health goal that is set at a level at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Source: U.S. Environmental Protection Agency.: 0 ppb
No
5 ppb
Lead (total)Lead is a metal that enters water by corrosion of household plumbing systems, discharge of industrial pollution and erosion of natural deposits.0.08 ppb
0.49 ppb
Yes
MCLGA non-enforceable health goal that is set at a level at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Source: U.S. Environmental Protection Agency.: 0 ppb
No
BromodichloromethaneBromodichloromethane is a disinfection byproduct from the trihalomethane (THM) family, and is formed when chlorine, chloramines or other disinfectants react with organic and inorganic matter in water.1.4 ppb
7.57 ppb
Yes
MCLGA non-enforceable health goal that is set at a level at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Source: U.S. Environmental Protection Agency.: 0 ppb
No
80 ppb
BromoformBromoform is a disinfection byproduct from the trihalomethane (THM) family, and is formed when chlorine, chloramines or other disinfectants react with organic and inorganic matter in water.0.07 ppb
1.33 ppb
Yes
MCLGA non-enforceable health goal that is set at a level at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Source: U.S. Environmental Protection Agency.: 0 ppb
No
80 ppb
Alpha particle activityAlpha particles are a form of radiation released from mining waste pollutants and natural sources.0.89 pCi/L
3.9 pCi/L
Yes
MCLGA non-enforceable health goal that is set at a level at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Source: U.S. Environmental Protection Agency.: 0 pCi/L
No
15 pCi/L
DibromochloromethaneDibromochloromethane is a disinfection byproduct from the trihalomethane (THM) family, and is formed when chlorine, chloramines or other disinfectants react with organic and inorganic matter in water.0.14 ppb
2.53 ppb
Yes
0.4 ppb
No
80 ppb
ChloroformChloroform is a disinfection byproduct from the trihalomethane (THM) family, and is formed when chlorine, chloramines or other disinfectants react with organic and inorganic matter in water.8.22 ppb
57.45 ppb
Yes
5.7 ppb
No
80 ppb
Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.9.93 ppb
65.8 ppb
Yes
9.8 ppb
No
80 ppb
Carbon tetrachlorideCarbon tetrachloride is an industrial solvent and refrigerant released as a pollutant from various chemical plants and the petroleum refining industry.<0.01 ppb
0.55 ppb
Yes
MCLGA non-enforceable health goal that is set at a level at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Source: U.S. Environmental Protection Agency.: 0 ppb
No
5 ppb
1,2-Dichloropropane1,2-Dichloropropane is used as a solvent and intermediate in the production of dry cleaning agent perchloroethylene; it is released as a pollutant from chemical factories, landfills, and from agricultural soil due to former use as a fumigant.<0.01 ppb
0.26 ppb
Yes
MCLGA non-enforceable health goal that is set at a level at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Source: U.S. Environmental Protection Agency.: 0 ppb
No
5 ppb
Radium-228Radium-228 is a radioactive element usually found around uranium deposits.<0.01 pCi/L
0.1 pCi/L
Yes
MCLGA non-enforceable health goal that is set at a level at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Source: U.S. Environmental Protection Agency.: 0 pCi/L
No
5 pCi/L
PerchloratePerchlorate is a synthetic oxygen additive in solid fuel propellant for rockets, missiles, and fireworks, and is primarily used by the military and the space industry; it may occur naturally in certain imported agricultural fertilizers.2.76 ppb
47 ppb
Yes
5 ppb
Legal at any levelThis is the Federal Limit. State Limits may be lower.
Combined Uranium (mg/L)Uranium is a radioactive element commonly found in most rocks; processed uranium ore is used for power generation and weapons manufacture.1.3 ppb
1.75 ppb
Yes
MCLGA non-enforceable health goal that is set at a level at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Source: U.S. Environmental Protection Agency.: 0 ppb
No
30 ppb
NOTE: Each dot in the above graph represents one month.
* Water utilities are noted as exceeding the legal limit if any test is above the maximum contaminant level (MCL). Most MCLs are based on annual averages so exceeding the MCL for one test does not necessarily indicate that the system is out of compliance.

Other Detected Contaminants

ContaminantAverage/
Maximum
Result
Health Limit
Exceeded
Legal Limit
Exceeded

Testing History

-Tested      -Detected      -Over Health Guidelines      -Over Legal Limit*
DichlorodifluoromethaneDichlorodifluoromethane (Freon 12) is a chlorofluorocarbon refrigerant and aerosol spray propellant; it was banned under the Montreal Protocol as of 2000 because of its ozone-depleting properties.0.45 ppb
10.28 ppb
No
1000 ppb
Legal at any levelThis is the Federal Limit. State Limits may be lower.
Barium (total)Barium is a mineral that enters drinking water through drilling and mining waste runoff, discharges from chemical industries and erosion of natural deposits.131.14 ppb
290 ppb
No
700 ppb
No
2000 ppb
Nitrate & nitriteNitrate and nitrite enter water from fertilizer runoff, leaching from septic tanks, and erosion of natural deposits.1.95 ppm
8.8 ppm
No
10 ppm
No
10 ppm
Chromium (total)Chromium is a metal that pollutes drinking water due to discharge from steel and pulp mills and erosion of natural deposits.3.97 ppb
13.68 ppb
No
100 ppb
No
100 ppb
VanadiumVanadium is a metal used as an alloying addition to iron & steel; it is discharged from ceramic, glass, textile, photography, metallurgy and rubber industries.14.88 ppb
29.61 ppb
NoLegal at any levelThis is the Federal Limit. State Limits may be lower.
AluminumAluminum is a metal released from metal refineries and mining operations.1.98 ppb
19.79 ppb
No
200 ppb
No
200 ppb
CopperCopper is a naturally occuring metal and drinking water contaminant that enters tap water by corrosion of household plumbing systems and erosion of natural deposits.1.14 ppb
6.51 ppb
No
300 ppb
No
1000 ppb
Mercury (total inorganic)Mercury is a metal from refinery and factory pollution, coal burning, landfill and agricultural runoff and erosion of natural deposits.0.03 ppb
0.17 ppb
No
1.2 ppb
No
2 ppb
Antimony (total)Antimony is a metal that enters water from petroleum refinery pollution, fire retardants, ceramics, electronics and solder.0.03 ppb
0.18 ppb
No
5.6 ppb
No
6 ppb
Selenium (total)Selenium is a naturally occurring element that contaminates water due to mining or petrolum refining, fly-ash from coal-burning power plants, and irrigation of arid farmland soils high in selenium.0.48 ppb
1.64 ppb
No
50 ppb
No
50 ppb
Beryllium (total)Beryllium is a metal associated with metal refineries and combustion of fossil fuels, especially coal burning; it is released into the environment from electrical, aerospace and defense industries.<0.01 ppb
0.02 ppb
No
1 ppb
No
4 ppb
Silver (total)Silver is an element from natural deposits and mining wastes; it is also associated with the development of photographic and x-ray film and the use of silver in antibacterial consumer products.0.09 ppb
0.85 ppb
No
100 ppb
No
100 ppb
Thallium (total)Thallium is a highly toxic metal that contaminates the environment due to leaching from ore-processing sites, discharge from electronics, glass, and drug factories and historical use as rodenticide<0.01 ppb
<0.01 ppb
No
0.1 ppb
No
2 ppb
NitriteNitrite is a chemical that enters water from fertilizer runoff, leaching septic tanks, and erosion of natural deposits.0.03 ppm
0.19 ppm
No
1 ppm
No
1 ppm
Combined Uranium (pCi/L)Uranium is a radioactive element commonly found in most rocks; processed ore is used for power generation and weapons manufacture.2.05 pCi/L
3.53 pCi/L
NoNo
15 pCi/L
Cadmium (total)Cadmium is a metal used in the steel and plastic industries; it is released from corrosion of galvanized pipes, runoff from metal refineries, waste batteries and paints; contamination from fertilizers; and erosion of natural deposits.<0.01 ppb
0.02 ppb
No
0.04 ppb
No
5 ppb
1,1,1-Trichloroethane1,1,1-Trichloroethane is an industrial cleaning solvent that contaminates drinking water sources due to releases from metal degreasing sites and chemicals factories.<0.01 ppb
0.1 ppb
No
200 ppb
No
200 ppb
NOTE: Each dot in the above graph represents one month.
* Water utilities are noted as exceeding the legal limit if any test is above the maximum contaminant level (MCL). Most MCLs are based on annual averages so exceeding the MCL for one test does not necessarily indicate that the system is out of compliance.

Contaminants Not Detected - 122 chemicals

1,1,1,2-Tetrachloroethane, 1,1,2,2-Tetrachloroethane, 1,1,2-Trichloroethane, 1,1-Dichloroethane, 1,1-Dichloroethylene, 1,1-Dichloropropene, 1,2 Dibromo-3-chloropropane (DBCP), 1,2,3-Trichlorobenzene, 1,2,3-Trichloropropane, 1,2,4-Trichlorobenzene, 1,2,4-Trimethylbenzene, 1,2-Dichloroethane, 1,3,5-Trimethylbenzene, 1,3-Dichloropropane, 1,3-Dichloropropene, 1,3-dinitrobenzene, 1,4-Dioxane, 2,2',4,4',5,5'-hexabromobiphenyl (hbb), 2,2',4,4',5,5'-hexabromodiphenyl Ether, 2,2',4,4',5-pentabromodiphenyl Ether, 2,2',4,4',6-pentabromodiphenyl Ether, 2,2',4,4'-tetrabromodiphenyl Ether, 2,2-Dichloropropane, 2,4,5-t, 2,4,5-TP (Silvex), 2,4,6-trinitrotoluene (tnt), 2,4-d, 2-Chloroethylvinyl ether, 3-Hydroxycarbofuran, Alachlor (Lasso), Aldicarb, Aldicarb sulfone, Aldicarb sulfoxide, Aldrin, Atrazine, Bentazon (Basagran), Benzene, Benzo[a]pyrene, Bromacil, Bromobenzene, Bromochloromethane, Bromomethane, Butachlor, Carbaryl, Carbofuran, Chlordane, Chloroethane, Chloromethane, Chlorothalonil (Bravo), cis-1,2-Dichloroethylene, cis-1,3-Dichloropropene, Cyanide, Dacthal, Dalapon, Di(2-Ethylhexyl) adipate, Di(2-ethylhexyl) phthalate, Diazinon (Spectracide), Dibromomethane, Dicamba, Dichloromethane (methylene chloride), Dieldrin, Dimethoate, Dinoseb, Diquat, Endothall, Endrin, Ethyl-t-butyl ether (ETBE), Ethylbenzene, Ethylene dibromide (EDB), Glyphosate, Heptachlor, Heptachlor epoxide, Hexachlorobenzene (HCB), Hexachlorobutadiene, Hexachlorocyclopentadiene, Isopropyl ether, Isopropylbenzene, Lindane, m- & p- Xylene, m-Dichlorobenzene, Methomyl, Methoxychlor, Methyl ethyl ketone, Methyl isobutyl ketone, Metolachlor, Metribuzin, Molinate (Ordram), Monochlorobenzene (Chlorobenzene), Mtbe, n-Butylbenzene, n-Propylbenzene, Naphthalene, Nitrobenzene, o-Chlorotoluene, o-Dichlorobenzene, o-Xylene, Oxamyl (Vydate), p-Chlorotoluene, p-Dichlorobenzene, p-Isopropyltoluene, Pentachlorophenol, Picloram, Prometryn, Propachlor, Rdx (hexahydro-1,3,5-trinitro-1,3,5-triazine), sec-Butylbenzene, Simazine, Styrene, Terbufos Sulfone, Tert-Amyl-Methyl Ether, tert-Butylbenzene, Thiobencarb (Bolero), Toluene, Total polychlorinated biphenyls (PCBs), Toxaphene, trans-1,2-Dichloroethylene, trans-1,3-Dichloropropene, Trichlorofluoromethane, Trichlorotrifluoroethane, Trifluralin, Vinyl chloride, Xylenes (total)

Pollution Summary

34Total Contaminants Detected (2004 - 2009)

Aluminum, Arsenic (total), Barium (total), Cadmium (total), Chromium (total), Copper, Lead (total), Manganese, Mercury (total inorganic), Nitrate & nitrite, Nitrate, Nitrite, Selenium (total), Silver (total), Antimony (total), Beryllium (total), Thallium (total), Vanadium, Dichlorodifluoromethane, Chloroform, Bromoform, Bromodichloromethane, Dibromochloromethane, Total trihalomethanes (TTHMs), 1,1,1-Trichloroethane, Carbon tetrachloride, 1,2-Dichloropropane, Trichloroethylene, Tetrachloroethylene, Combined Uranium (mg/L), Radium-228, Alpha particle activity, Perchlorate, Combined Uranium (pCi/L)

7Agricultural Pollutants
(pesticides, fertilizer, factory farms)

Arsenic (total), Nitrate & nitrite, Nitrate, Nitrite, Selenium (total), 1,2-Dichloropropane, Perchlorate

11Sprawl and Urban Pollutants
(road runoff, lawn pesticides, human waste)

Nitrate, Copper, Nitrate & nitrite, Lead (total), Arsenic (total), Tetrachloroethylene, Nitrite, Cadmium (total), Antimony (total), Mercury (total inorganic), Silver (total)

28Industrial Pollutants

Aluminum, Arsenic (total), Barium (total), Cadmium (total), Chromium (total), Lead (total), Manganese, Mercury (total inorganic), Nitrate & nitrite, Nitrate, Nitrite, Selenium (total), Silver (total), Antimony (total), Beryllium (total), Thallium (total), Vanadium, Dichlorodifluoromethane, 1,1,1-Trichloroethane, Carbon tetrachloride, 1,2-Dichloropropane, Trichloroethylene, Tetrachloroethylene, Combined Uranium (mg/L), Radium-228, Alpha particle activity, Perchlorate, Combined Uranium (pCi/L)

6Water Treatment and Distribution Byproducts
(pipes and fixtures, treatment chemicals and byproducts)

Total trihalomethanes (TTHMs), Chloroform, Bromodichloromethane, Dibromochloromethane, Bromoform, Cadmium (total)

17Naturally Occurring
(naturally present but increased for lands denuded by sprawl, agriculture, or industrial development)

Nitrate, Copper, Nitrate & nitrite, Barium (total), Lead (total), Arsenic (total), Manganese, Radium-228, Alpha particle activity, Combined Uranium (pCi/L), Chromium (total), Combined Uranium (mg/L), Aluminum, Selenium (total), Nitrite, Mercury (total inorganic), Silver (total)

4Unregulated Contaminants
EPA has not established a maximum legal limit in tapwater for these contaminants

Lead (total), Vanadium, Dichlorodifluoromethane, Perchlorate

EPA Violation Summary

No violations were reported for this system since 2004.

Information on violations is drawn directly from EPA's national violations database in the Agency's Safe Drinking Water Information System. Analyses by others have raised questions about the quality of the information in EPA's database. For the purposes of this investigation, EWG is not showing below or including in our analyses, those violations for individual water suppliers that occurred on days for which the total number of violations assigned by EPA to that water supplier was greater than 20. This criteria was based on common characteristics of incorrect violations data as identified by water utilities, from a review of EPA's violations data by several hundred utilities prior to the release of EWG's investigation.