847 systems serving 3,320,844 people
  This drinking water quality report shows results of tests conducted by water utilities in Oklahoma, provided to the Environmental Working Group (EWG) by the Oklahoma 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.

  22 Contaminants Exceeding Health Based Limits

Contaminants detected in Oklahoma 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
Total haloacetic acids (HAAs) 2,881,375 2,881,375 600 600
Total trihalomethanes (TTHMs) 2,910,505 2,786,112 636 510
Lead (total) 2,326,065 2,326,065 307 307
Arsenic (total) 1,069,000 1,069,000 2 2
Combined Uranium (mg/L) 811,370 811,370 52 52
Bromodichloromethane 471,000 471,000 1 1
Dibromochloromethane 471,000 471,000 1 1
Chloroform 471,000 471,000 1 1
Copper 2,939,348 311,623 596 105
Benzene 84,452 84,452 7 7

  Sources of Oklahoma Drinking Water Contaminants

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

39 Total Contaminants Detected (2004 - 2009)
8 Agricultural Pollutants
(pesticides, fertilizer, factory farms)

Arsenic (total), Nitrate & nitrite, Nitrate, Selenium (total), Atrazine, p-Dichlorobenzene, Monochlorobenzene (Chlorobenzene), Ethylbenzene

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

Arsenic (total), Cadmium (total), Copper, Lead (total), Mercury (total inorganic), Nitrate & nitrite, Nitrate, Antimony (total), Xylenes (total), Dichloromethane (methylene chloride), p-Dichlorobenzene, Tetrachloroethylene, Benzene

32 Industrial Pollutants

Aluminum, Arsenic (total), Barium (total), Cadmium (total), Chromium (total), Lead (total), Manganese, Mercury (total inorganic), Nitrate & nitrite, Nitrate, Selenium (total), Antimony (total), Beryllium (total), Thallium (total), 1,2,4-Trichlorobenzene, cis-1,2-Dichloroethylene, Xylenes (total), Dichloromethane (methylene chloride), p-Dichlorobenzene, Vinyl chloride, 1,1-Dichloroethylene, 1,1-Dichloroethane, 1,2-Dichloroethane, Carbon tetrachloride, Trichloroethylene, Tetrachloroethylene, Monochlorobenzene (Chlorobenzene), Benzene, Toluene, Ethylbenzene, Styrene, Combined Uranium (mg/L)

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

Total trihalomethanes (TTHMs), Total haloacetic acids (HAAs), Chloroform, Bromodichloromethane, Dibromochloromethane, Cadmium (total), Vinyl chloride

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

Aluminum, Arsenic (total), Barium (total), Chromium (total), Copper, Lead (total), Manganese, Mercury (total inorganic), Nitrate & nitrite, Nitrate, Selenium (total), Combined Uranium (mg/L)

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

Lead (total), 1,1-Dichloroethane

  Testing Summary for Oklahoma

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

Contaminants reported as tested by water suppliers in Oklahoma 102
  Contaminants tested due to federal law: 65
  Contaminants tested in addition to those required by federal law: 37
  Violation Summary for Oklahoma

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

Violation Type Number of Violations
Over maximum contaminant level, Average 2,605
Failure to monitor, Routine Major (Coliform bacteria) 2,182
Failure to monitor regularly 2,174
Monitoring and Reporting Disinfection Byproduct Rule 1,020
Treatment Technique Precursor Removal 974
Maximum contaminant level, Monthly (Coliform bacteria) 489
Failure to monitor, Routine Minor (Coliform bacteria) 485
Excess Turbidity at 0.3 NTU 266
Filter Turbidity Reporting 252
Over maximum contaminant level, Single Sample 242
Failure to monitor, Repeat Major (Coliform bacteria) 203
Excess Turbidity at 1 NTU 84
Failure to monitor, Repeat Minor (Coliform bacteria) 59
Failure to monitor or report, Routine/Repeat (Indicators of microbial or virus contamination) 51
Follow-up and Routine Tap Sampling 39
Maximum contaminant level, Acute (Coliform bacteria) 35
Treatment Technique (Surface Water Treatment Rule) 33
Initial Tap Sampling for Lead and Copper 4
Non-Acute maximum residual disinfectant level 3
Public Notification Violation for National Primary Drinking Water Regulations 1

Sources : EWG (Environmental Working Group)