The Power of Information

National Drinking Water Database


Diablo Water District - Concord, CA


Serves 33,250 people - Test data available: 2004-2008

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.
13 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.
0 chemicals
0.5
Pollutants FoundThe total number of contaminants detected since 2004, according to data provided by the state water agency.
26 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.
1,341 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*
BromateBromate is a carcinogenic disinfection byproduct of ozonation formed when source waters contain high levels of natural bromide; it can also form following water treatment with chlorine dioxide or hypochlorite.0.76 ppb
9.2 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
10 ppb
Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.3.55 ppb
13.6 ppb
Yes
0.7 ppb
No
60 ppb
Dichloroacetic acidDichloroacetic acid is a disinfection byproduct regulated by EPA as one of five haloacetic acids that are formed when chlorine, chloramines or other disinfectants react with organic and inorganic matter in water.1.01 ppb
3 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
60 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.0.27 ppb
2 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
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.0.69 ppb
5.9 ppb
Yes
0.4 ppb
No
80 ppb
RadonRadon is a radioactive breakdown product of radium and uranium in soil, rock and water; it is often present in groundwater.495 pCi/L
576 pCi/L
Yes
1.5 pCi/L
Legal at any levelThis is the Federal Limit. State Limits may be lower.
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.0.77 ppb
9.4 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
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.4.73 ppb
5.8 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
Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.2.27 ppb
24.1 ppb
Yes
9.8 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.0.53 ppb
8 ppb
Yes
5.7 ppb
No
80 ppb
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.0.2 ppb
3 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
10 ppb
Radium-226Radium-226 is a radioactive element usually found around uranium deposits.0.22 pCi/L
1.09 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
Alpha particle activityAlpha particles are a form of radiation released from mining waste pollutants and natural sources.0.82 pCi/L
4.1 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
15 pCi/L
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*
BromideBromide is a naturally occurring element found in surface waters and groundwater and contributes to the formation of toxic tap water disinfection byproducts.148.77 ppb
500 ppb
NoLegal at any levelThis is the Federal Limit. State Limits may be lower.
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.0.28 ppm
1.24 ppm
No
10 ppm
No
10 ppm
Dibromoacetic acidDibromoacetic acid is a disinfection byproduct regulated by EPA as one of five haloacetic acids that are formed when chlorine, chloramines or other disinfectants react with organic and inorganic matter in water.1.04 ppb
2.3 ppb
NoNo
60 ppb
ChlorateChlorate is a disinfection byproduct (unregulated chlorine dioxide byproduct), an herbicide and a pollutant from explosives.380.11 ppb
690 ppb
NoLegal at any levelThis is the Federal Limit. State Limits may be lower.
Combined Uranium (pCi/L)Uranium is a radioactive element commonly found in most rocks; processed ore is used for power generation and weapons manufacture.3.16 pCi/L
3.9 pCi/L
NoNo
15 pCi/L
VanadiumVanadium is a metal used as an alloying addition to iron & steel; it is discharged from ceramic, glass, textile, photography, metallurgy and rubber industries.5.03 ppb
5.5 ppb
NoLegal at any levelThis is the Federal Limit. State Limits may be lower.
Chromium (hexavalent)Chromium is a metal that pollutes drinking water due to discharge from steel and pulp mills and erosion of natural deposits.1.55 ppb
1.6 ppb
NoNo
100 ppb
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.24 ppb
130 ppb
No
700 ppb
No
2000 ppb
Monochloroacetic acidMonochloroacetic acid is a disinfection byproduct regulated by EPA as one of five haloacetic acids that are formed when chlorine, chloramines or other disinfectants react with organic and inorganic matter in water.0.39 ppb
3.6 ppb
No
70 ppb
No
60 ppb
Trichloroacetic acidTrichloroacetic acid is a disinfection byproduct regulated by EPA as one of five haloacetic acids that are formed when chlorine, chloramines or other disinfectants react with organic and inorganic matter in water.0.24 ppb
2.3 ppb
No
20 ppb
No
60 ppb
Monobromoacetic acidMonobromoacetic acid is a disinfection byproduct regulated by EPA as one of five haloacetic acids that are formed when chlorine, chloramines or other disinfectants react with organic and inorganic matter in water.0.59 ppb
6.8 ppb
NoNo
60 ppb
ManganeseManganese is a naturally occurring element released from mineral deposits as well as industrial use.2.53 ppb
38 ppb
No
50 ppb
No
50 ppb
AluminumAluminum is a metal released from metal refineries and mining operations.5.77 ppb
86.6 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 - 145 chemicals

1,1,1,2-Tetrachloroethane, 1,1,1-Trichloroethane, 1,1,2,2-Tetrachloroethane, 1,1,2-Trichloroethane, 1,1-Dichloroethane, 1,1-Dichloroethylene, 1,1-dichloropropane, 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, 1,2-Dichloropropane, 1,3,5-Trimethylbenzene, 1,3-Dichloropropane, 1,3-Dichloropropene, 2,2-Dichloropropane, 2,3,7,8-TCDD (Dioxin), 2,4,5-TP (Silvex), 2,4-d, 2-Chloroethylvinyl ether, 3-Hydroxycarbofuran, Acetochlor, Alachlor (Lasso), Aldicarb, Aldicarb sulfone, Aldicarb sulfoxide, Aldrin, Antimony (total), Aroclor 1221, Aroclor 1232, Aroclor 1242, Aroclor 1248, Aroclor 1254, Aroclor 1260, Asbestos, Atrazine, Bentazon (Basagran), Benzene, Benzo[a]pyrene, Beryllium (total), Bromacil, Bromobenzene, Bromochloromethane, Bromomethane, Butachlor, Cadmium (total), Caffeine, Carbaryl, Carbofuran, Carbon tetrachloride, Chlordane, Chlorite, Chloroethane, Chloromethane, Chlorothalonil (Bravo), Chromium (total), cis-1,2-Dichloroethylene, Copper, Cyanide, Dacthal, Dalapon, Di(2-Ethylhexyl) adipate, Di(2-ethylhexyl) phthalate, Diazinon (Spectracide), Dibromomethane, Dicamba, Dichlorodifluoromethane, Dichloromethane (methylene chloride), Dieldrin, Dimethoate, Dinitro-o-cresol, Dinoseb, Diquat, Endothall, Endrin, Ethyl-t-butyl ether (ETBE), Ethylbenzene, Ethylene dibromide (EDB), Glyphosate, Gross beta particle activity (pCi/L), Heptachlor, Heptachlor epoxide, Hexachlorobenzene (HCB), Hexachlorobutadiene, Hexachlorocyclopentadiene, Isopropyl ether, Isopropylbenzene, Lead (total), Lindane, m- & p- Xylene, m-Dichlorobenzene, Mercury (total inorganic), Methomyl, Methoxychlor, Methyl ethyl ketone, Methyl isobutyl ketone, Metolachlor, Metribuzin, Molinate (Ordram), Monochlorobenzene (Chlorobenzene), Mtbe, n-Butylbenzene, n-Propylbenzene, Naphthalene, Nitrite, o-Chlorotoluene, o-Dichlorobenzene, o-Xylene, Oxamyl (Vydate), p-Chlorotoluene, p-Dichlorobenzene, p-Isopropyltoluene, Parachlorometacresol, Pentachlorophenol, Perchlorate, Picloram, Prometryn, Propachlor, Radium-228, sec-Butylbenzene, Selenium (total), Silver (total), Simazine, Strontium-90, Styrene, Terbacil, Tert-Amyl-Methyl Ether, Tert-Butyl Alcohol, tert-Butylbenzene, Tetrachloroethylene, Thallium (total), Thiobencarb (Bolero), Toluene, Total polychlorinated biphenyls (PCBs), Toxaphene, trans-1,2-Dichloroethylene, Trichloroethylene, Trichlorofluoromethane, Trichlorotrifluoroethane, Tritium, Vinyl chloride, Xylenes (total)

Pollution Summary

26Total Contaminants Detected (2004 - 2008)

Aluminum, Bromide, Chlorate, Barium (total), Manganese, Nitrate, Chromium (hexavalent), Vanadium, Monochloroacetic acid, Trichloroacetic acid, Monobromoacetic acid, Dibromoacetic acid, Combined Uranium (pCi/L), Arsenic (total), Bromate, Dichloroacetic acid, Total haloacetic acids (HAAs), Chloroform, Bromoform, Bromodichloromethane, Dibromochloromethane, Total trihalomethanes (TTHMs), Radon, Combined Uranium (mg/L), Radium-226, Alpha particle activity

3Agricultural Pollutants
(pesticides, fertilizer, factory farms)

Chlorate, Nitrate, Arsenic (total)

2Sprawl and Urban Pollutants
(road runoff, lawn pesticides, human waste)

Nitrate, Arsenic (total)

13Industrial Pollutants

Aluminum, Bromide, Chlorate, Barium (total), Manganese, Nitrate, Chromium (hexavalent), Vanadium, Combined Uranium (pCi/L), Arsenic (total), Combined Uranium (mg/L), Radium-226, Alpha particle activity

13Water Treatment and Distribution Byproducts
(pipes and fixtures, treatment chemicals and byproducts)

Total trihalomethanes (TTHMs), Total haloacetic acids (HAAs), Chloroform, Bromodichloromethane, Dibromochloromethane, Dichloroacetic acid, Trichloroacetic acid, Bromoform, Dibromoacetic acid, Monochloroacetic acid, Monobromoacetic acid, Chlorate, Bromate

12Naturally Occurring
(naturally present but increased for lands denuded by sprawl, agriculture, or industrial development)

Nitrate, Barium (total), Arsenic (total), Manganese, Radium-226, Alpha particle activity, Combined Uranium (pCi/L), Combined Uranium (mg/L), Aluminum, Radon, Bromide, Chromium (hexavalent)

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

Bromide, Chlorate, Vanadium, Radon

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.