753 systems serving 4,995,854 people
  This drinking water quality report shows results of tests conducted by water utilities in Arizona, provided to the Environmental Working Group (EWG) by the Arizona Department of Environmental Quality. It is part of EWG's national database that includes 47,667 drinking water utilities and 20 million test results from 45 states and the District of Columbia. 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 in protecting rivers, reservoirs, and groundwater from pollution in the first place. The information below summarizes drinking water quality for this state.

Water Utilities
Population Served
Detected Chemicals
Exceed health guidelines*
Exceed Legal Limits*
Unregulated chemicals detected
* 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.
  36 Contaminants Exceeding Health Based Limits

Contaminants detected in Arizona drinking water above health guidelines, according to an Environmental Working Group analysis of data obtained from state water authorities.

Number of Systems
At Any Level Above Health Limits At Any Level Above Health Limits
Arsenic (total) 4,596,872 4,596,872 501 501
Total haloacetic acids (HAAs) 4,361,892 4,281,536 186 175
Alpha particle activity (excl radon and uranium) 3,845,801 3,845,801 66 66
Di(2-ethylhexyl) phthalate 3,325,680 3,325,680 43 43
Bromoform 3,314,082 3,314,082 223 223
Dibromochloromethane 3,234,784 3,229,824 192 189
Total trihalomethanes (TTHMs) 4,633,570 3,102,899 286 105
Bromodichloromethane 2,958,632 2,958,632 144 144
Lead (total) 2,704,593 2,704,593 380 380
Dichloroacetic acid 2,441,551 2,441,551 70 70

  Sources of Arizona Drinking Water Contaminants

The contaminants identified in Arizona drinking water come from a wide variety of sources, including agriculture, industry, water treatment plants, and polluted storm runoff from urban areas.

68 Total Contaminants Detected (2004 - 2009)
17 Agricultural Pollutants
(pesticides, fertilizer, factory farms)

Arsenic (total), Cyanide, Nitrate & nitrite, Nitrate, Nitrite, Selenium (total), Dalapon, Diquat, Simazine, Dinoseb, Atrazine, 2,4-D, 1,2-Dibromo-3-chloropropane (DBCP), Ethylene dibromide (EDB), Chlordane, p-Dichlorobenzene, Ethylbenzene

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

Nitrate, Copper, Nitrate & nitrite, Lead (total), Arsenic (total), Tetrachloroethylene, Nitrite, Xylenes (total), Dalapon, Cadmium (total), Antimony (total), Mercury (total inorganic), Cyanide, p-Dichlorobenzene, 2,4-D, Chlordane, Benzo[a]pyrene, 2,3,7,8-TCDD (Dioxin)

43 Industrial Pollutants

Arsenic (total), Chlorite, Barium (total), Cadmium (total), Chromium (total), Cyanide, Lead (total), Mercury (total inorganic), Nitrate & nitrite, Nitrate, Nitrite, Selenium (total), Antimony (total), Beryllium (total), Thallium (total), Asbestos, Di(2-ethylhexyl) phthalate, Hexachlorocyclopentadiene, 2,3,7,8-TCDD (Dioxin), Hexachlorobenzene (HCB), Pentachlorophenol, cis-1,2-Dichloroethylene, Ethylene dibromide (EDB), Xylenes (total), p-Dichlorobenzene, Vinyl chloride, 1,1-Dichloroethylene, 1,1-Dichloroethane, Trichloroethylene, Tetrachloroethylene, Toluene, Ethylbenzene, Styrene, Alpha particle activity (excl radon and uranium), Alpha particle activity (incl. radon & uranium), Combined Uranium (mg/L), Uranium-234, Uranium-235, Uranium-238, Combined Radium (-226 & -228), Radium-226, Radium-228, Combined Uranium (pCi/L)

18 Water 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, Chlorite, Di(2-ethylhexyl) phthalate, Cadmium (total), Bromate, Vinyl chloride, Asbestos, Benzo[a]pyrene

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

Nitrate, Copper, Nitrate & nitrite, Barium (total), Lead (total), Arsenic (total), Radium-228, Radium-226, Alpha particle activity (excl radon and uranium), Combined Radium (-226 & -228), Combined Uranium (pCi/L), Chromium (total), Alpha particle activity (incl. radon & uranium), Combined Uranium (mg/L), Selenium (total), Nitrite, Radon, Mercury (total inorganic), Cyanide, Uranium-238, Uranium-234, Uranium-235

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

Lead (total), 1,1-Dichloroethane, Radon, Uranium-234 (pCi/L), Uranium-238 (pCi/L)

  Testing Summary for Arizona

The federal government has set standards for some of the pollutants found in tap water supplies.

Contaminants reported as tested by water suppliers in Arizona 156
  Contaminants tested due to federal law: 99
  Contaminants tested in addition to those required by federal law: 57
  Violation Summary for Arizona

Data from the U.S. Environmental Protection Agency includes the following violations of federal standards in Arizona since 2004.

Violation Type Number of Violations
Failure to monitor regularly 6,280
Monitoring and Reporting Disinfection Byproduct Rule 5,411
Failure to monitor, Routine Major (Coliform bacteria) 2,963
Failure to report information to the public or state agency in the Consumer Confidence Report 1,871
Follow-up and Routine Tap Sampling 918
Failure to monitor, Routine Minor (Coliform bacteria) 852
Failure to monitor, Repeat Major (Coliform bacteria) 428
Maximum contaminant level, Monthly (Coliform bacteria) 304
Over maximum contaminant level, Average 271
Initial Tap Sampling for Lead and Copper 262
Failure to monitor, Repeat Minor (Coliform bacteria) 98
Over maximum contaminant level, Single Sample 86
Filter Turbidity Reporting 81
Failure to monitor: Check/Repeat/Confirmation sampling 28
Maximum contaminant level, Acute (Coliform bacteria) 9
Non-Acute maximum residual disinfectant level 9
Treatment Technique (Surface Water Treatment Rule) 2
Excess Turbidity at 1 NTU 1
Inadequate reporting of information to the public 1

Sources : EWG (Environmental Working Group)