478 systems serving 5,156,372 people
  This drinking water quality report shows results of tests conducted by water utilities in Maryland, provided to the Environmental Working Group (EWG) by the Maryland Department of Environment. 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.

  50 Contaminants Exceeding Health Based Limits

Contaminants detected in Maryland 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
Bromodichloromethane 5,097,416 5,097,416 314 314
Dibromochloromethane 5,044,515 5,043,781 259 256
Total haloacetic acids (HAAs) 5,020,623 5,013,963 251 232
Dichloroacetic acid 4,966,181 4,966,181 174 174
Total trihalomethanes (TTHMs) 5,116,257 4,815,049 371 156
Chloroform 5,097,509 4,792,226 360 147
Di(2-ethylhexyl) phthalate 4,785,076 4,785,076 308 308
Bromoform 4,325,788 4,325,788 105 105
Alpha particle activity (excl radon and uranium) 4,301,561 4,301,561 168 168
Trichloroacetic acid 4,907,602 4,132,302 209 40

  Sources of Maryland Drinking Water Contaminants

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

93 Total Contaminants Detected (2004 - 2007)
35 Agricultural Pollutants
(pesticides, fertilizer, factory farms)

Arsenic (total), Cyanide, Nitrate, Nitrite, Selenium (total), Endrin, Lindane, Methoxychlor, Dalapon, Simazine, Picloram, Dinoseb, Aldicarb sulfoxide, Metolachlor, Atrazine, Alachlor (Lasso), Heptachlor, 3-Hydroxycarbofuran, Heptachlor epoxide, Dieldrin, Butachlor, Propachlor, 2,4-D, 2,4,5-TP (Silvex), 2,4,5-T, Aldrin, Dicamba, Metribuzin, 1,2-Dibromo-3-chloropropane (DBCP), Ethylene dibromide (EDB), Chlordane, p-Dichlorobenzene, Monochlorobenzene (Chlorobenzene), Ethylbenzene, Perchlorate

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

Nitrate, Copper, Lead (total), Arsenic (total), Tetrachloroethylene, MTBE, Nitrite, Xylenes (total), Dalapon, Cadmium (total), Antimony (total), Mercury (total inorganic), Dichloromethane (methylene chloride), Cyanide, o-Xylene, Benzene, p-Dichlorobenzene, Di(2-Ethylhexyl) adipate, 2,4-D, p-Xylene, m-Xylene, Chlordane, Benzo[a]pyrene, Lindane, 2,4,5-TP (Silvex), 2,4,5-T

51 Industrial Pollutants

Aluminum, Arsenic (total), Barium (total), Cadmium (total), Chromium (total), Cyanide, Lead (total), Manganese, Mercury (total inorganic), Nitrate, Nitrite, Selenium (total), Antimony (total), Beryllium (total), Thallium (total), Lindane, p-Isopropyltoluene, Di(2-Ethylhexyl) adipate, Di(2-ethylhexyl) phthalate, Hexachlorocyclopentadiene, Chloromethane, MTBE, Hexachlorobenzene (HCB), Pentachlorophenol, cis-1,2-Dichloroethylene, Dichlorobiphenyl, Ethylene dibromide (EDB), Xylenes (total), p-Xylene, Dichloromethane (methylene chloride), p-Dichlorobenzene, 1,1-Dichloroethylene, 1,2-Dichloroethane, 1,1,1-Trichloroethane, Carbon tetrachloride, Trichloroethylene, Tetrachloroethylene, Monochlorobenzene (Chlorobenzene), Benzene, Toluene, Ethylbenzene, Isopropylbenzene, m-Xylene, o-Xylene, Alpha particle activity (excl radon and uranium), Combined Radium (-226 & -228), Radium-226, Radium-228, Perchlorate, Combined Uranium (pCi/L), Gross beta particle activity (pCi/L)

17 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, Bromochloroacetic acid, Monobromoacetic acid, Di(2-ethylhexyl) phthalate, Cadmium (total), Chloromethane, Benzo[a]pyrene, Chlorodibromoacetic acid

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

Nitrate, Copper, Barium (total), Lead (total), Arsenic (total), Manganese, Radium-228, Radium-226, Alpha particle activity (excl radon and uranium), Combined Radium (-226 & -228), Gross beta particle activity (pCi/L), Combined Uranium (pCi/L), Chromium (total), Aluminum, Selenium (total), Nitrite, Radon, Mercury (total inorganic), Chloromethane, Cyanide

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

Lead (total), p-Isopropyltoluene, Aldicarb sulfoxide, Metolachlor, 3-Hydroxycarbofuran, Dieldrin, Butachlor, Propachlor, 2,4,5-T, Chloromethane, MTBE, Aldrin, Dichlorobiphenyl, Dicamba, Bromochloroacetic acid, Metribuzin, Isopropylbenzene, Radon, Perchlorate, Chlorodibromoacetic acid, Uranium-234 (pCi/L), Uranium-238 (pCi/L)

  Testing Summary for Maryland

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

Contaminants reported as tested by water suppliers in Maryland 141
  Contaminants tested due to federal law: 85
  Contaminants tested in addition to those required by federal law: 56
  Violation Summary for Maryland

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

Violation Type Number of Violations
Failure to monitor, Routine Major (Coliform bacteria) 518
Failure to monitor regularly 227
Failure to report information to the public or state agency in the Consumer Confidence Report 207
Over maximum contaminant level, Average 126
Follow-up and Routine Tap Sampling 116
Maximum contaminant level, Monthly (Coliform bacteria) 68
Monitoring and Reporting Disinfection Byproduct Rule 24
Initial Tap Sampling for Lead and Copper 12
Failure to monitor, Repeat Major (Coliform bacteria) 10
Excess Turbidity at 0.3 NTU 9
Failure to monitor, Repeat Minor (Coliform bacteria) 8
Public Education 7
Optimal Corrosion Control Treatment Study Recommendation 7
Initial, Follow-up, or Routine Source Water Treatment Monitoring and Reporting 6
Over maximum contaminant level, Single Sample 5
Failure to monitor, Routine Minor (Coliform bacteria) 5
Treatment Technique (Surface Water Treatment Rule) 5
Excess Turbidity at 1 NTU 5
Inadequate reporting of information to the public 4
Maximum contaminant level, Acute (Coliform bacteria) 4
Initial Water Quality Parameter Monitoring and Reporting 4
Failure to notify public of violation 3
Filter Turbidity Reporting 3
Failure to Filter (Surface Water Treatment Rule) 3
Failure to monitor or report, Routine/Repeat (Indicators of microbial or virus contamination) 2
Treatment Technique Precursor Removal 1
Failure to monitor or report, Routine/Repeat (Indicators of microbial or virus contamination) 1

Sources : EWG (Environmental Working Group)