The Power of Information

National Drinking Water Database


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)2,881,3752,881,375600600
Total trihalomethanes (TTHMs)2,910,5052,786,112636510
Lead (total)2,326,0652,326,065307307
Arsenic (total)1,069,0001,069,00022
Combined Uranium (mg/L)811,370811,3705252

Water Utilities in Oklahoma Reporting Chemicals Exceeding Health Guidelines

Water utilities in Oklahoma reporting chemicals exceeding health guidelines, according to an Environmental Working Group analysis of data obtained from state water authorities, include:

Chemicals tested
Chemicals found
Chemicals exceeding
health guidelines
City of Tulsa Water Supply System471,00076148
Delaware Co Rwd #101,40039126
Marshall County Water Corp13,74237126
Tillman Co Rwd #11,2005595
Logan Co Rws & Swmd #31,6184565
North Blaine Water1,5003965
Pottawatomie County Rwd #35603985
Del City22,1283975
Sand Springs17,4513965
Sardis Lake Water Authority3073765
Dill City5263774
Konawa Pwa1,4793454
Ripley Pwa4443454
Okmulgee Co Rwd #5 (Bryant Rwd #5)7503674
Red Rock2933654
Haskell Pwa1,7651254
Mcintosh Co Rwd #12 (Shell Creek)1753654
Hanna Pwa1334754

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.

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

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

13Sprawl 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

32Industrial 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)

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

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

12Naturally 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)

2Unregulated 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 Oklahoma102
 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 TypeNumber of Violations
Over maximum contaminant level, Average2,605
Failure to monitor, Routine Major (Coliform bacteria)2,182
Failure to monitor regularly2,174
Monitoring and Reporting Disinfection Byproduct Rule1,020
Treatment Technique Precursor Removal974
Maximum contaminant level, Monthly (Coliform bacteria)489
Failure to monitor, Routine Minor (Coliform bacteria)485
Excess Turbidity at 0.3 NTU266
Filter Turbidity Reporting252
Over maximum contaminant level, Single Sample242
Failure to monitor, Repeat Major (Coliform bacteria)203
Excess Turbidity at 1 NTU84
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 Sampling39
Maximum contaminant level, Acute (Coliform bacteria)35
Treatment Technique (Surface Water Treatment Rule)33
Initial Tap Sampling for Lead and Copper4
Non-Acute maximum residual disinfectant level3
Public Notification Violation for National Primary Drinking Water Regulations1