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EWG's Tap Water Database — 2019 UPDATE

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D.C. Water and Sewer Authority

EWG's drinking water quality report shows results of tests conducted by the water utility and provided to the Environmental Working Group by the Army Corps of Engineers and EPA Region 3, as well as information from the U.S. EPA Enforcement and Compliance History database (ECHO). For the latest quarter assessed by the U.S. EPA (January 2019 - March 2019), tap water provided by this water utility was in compliance with federal health-based drinking water standards.

Utility Details

  • Washington, District Of Columbia
  • Serves: 632,323
  • Data available: 2012—2017
  • Source: Purchased surface water

Contaminants Detected

9

EXCEED
EWG HEALTH
GUIDELINES

36 Total Contaminants

  • Legal does not necessarily equal safe. Getting a passing grade from the federal government does not mean the water meets the latest health guidelines.
  • Legal limits for contaminants in tap water have not been updated in almost 20 years.
  • The best way to ensure clean tap water is to keep pollution out of source water in the first place.

Legal ≠ Safe

EWG Health Guidelines fill the gap in outdated government standards.

The federal government’s legal limits are not health-protective. The EPA has not set a new tap water standard in almost 20 years, and some standards are more than 40 years old.

Contaminants Detected

Arsenic*

Potential Effect: cancer34x EWG'S HEALTH GUIDELINE
THIS UTILITY0.137 ppb
EWG HEALTH GUIDELINE0.004 ppb
LEGAL LIMIT10 ppb
DETAILS
X

Arsenic is a potent carcinogen and common contaminant in drinking water. Arsenic causes thousands of cases of cancer each year in the U.S. Click here to read more about arsenic.

Arsenic was found at 34 times above EWG's Health Guideline.

EWG Health Guideline

0.004 ppb or less

This Utility

0.137 ppb

Legal Limit

10 ppb

National Average

0.688 ppb

State Average

0.129 ppb
The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2015-2017.
ppb = parts per billion

Health Risks

The EWG Health Guideline of 0.004 ppb for arsenic was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer.

Pollution Sources

agriculture icon

Agriculture

industry icon

Industry

naturally occuring icon

Naturally Occurring

Filtering Options

reverse osmosis icon

Reverse Osmosis

ion exchange icon

Ion Exchange

Bromodichloromethane

Potential Effect: cancer194x EWG'S HEALTH GUIDELINE
THIS UTILITY11.7 ppb
EWG HEALTH GUIDELINE0.06 ppb
NO LEGAL LIMIT
DETAILS
X

Bromodichloromethane

more about
this contaminant

Bromodichloromethane, one of the total trihalomethanes (TTHMs), is formed when chlorine or other disinfectants are used to treat drinking water. Bromodichloromethane and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Click here to read more about disinfection byproducts.

Bromodichloromethane was found at 194 times above EWG's Health Guideline.

EWG Health Guideline

0.06 ppb or less

This Utility

11.7 ppb

National Average

5.77 ppb

State Average

10.3 ppb
NO LEGAL LIMIT
The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2015-2017.
ppb = parts per billion

Health Risks

The EWG Health Guideline of 0.06 ppb for bromodichloromethane was proposed in 2018 by the California Office of Environmental Health Hazard Assessment as a one-in-a-million lifetime risk of cancer. Values greater than one-in-a-million cancer risk level can result in increased cancer cases above one in a million people.

Pollution Sources

water treatment icon

Treatment Byproducts

Filtering Options

carbon filter icon

Activated Carbon

reverse osmosis icon

Reverse Osmosis

Chloroform

Potential Effect: cancer64x EWG'S HEALTH GUIDELINE
THIS UTILITY25.5 ppb
EWG HEALTH GUIDELINE0.4 ppb
NO LEGAL LIMIT
DETAILS
X

Chloroform, one of the total trihalomethanes (TTHMs), is formed when chlorine or other disinfectants are used to treat drinking water. Chloroform and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy.

Chloroform was found at 64 times above EWG's Health Guideline.

EWG Health Guideline

0.4 ppb or less

This Utility

25.5 ppb

National Average

15 ppb

State Average

24.3 ppb
NO LEGAL LIMIT
The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2015-2017.
ppb = parts per billion

Health Risks

The EWG Health Guideline of 0.4 ppb for chloroform was proposed in 2018 by the California Office of Environmental Health Hazard Assessment as a one-in-a-million lifetime risk of cancer. Values greater than one-in-a-million cancer risk level can result in increased cancer cases above one in a million people.

Pollution Sources

water treatment icon

Treatment Byproducts

Filtering Options

carbon filter icon

Activated Carbon

reverse osmosis icon

Reverse Osmosis

Chromium (hexavalent)

Potential Effect: cancer4.3x EWG'S HEALTH GUIDELINE
THIS UTILITY0.0863 ppb
EWG HEALTH GUIDELINE0.02 ppb
NO LEGAL LIMIT
DETAILS
X

Chromium (hexavalent)

more about
this contaminant

Chromium (hexavalent) is a carcinogen that commonly contaminates American drinking water. Chromium (hexavalent) in drinking water may be due to industrial pollution or natural occurrences in mineral deposits and groundwater. Read more about chromium (hexavalent).

Chromium (hexavalent) was found at 4.3 times above EWG's Health Guideline.

EWG Health Guideline

0.02 ppb or less

This Utility

0.0863 ppb

National Average

0.492 ppb

State Average

0.086 ppb
NO LEGAL LIMIT
The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2012-2017.
ppb = parts per billion

Health Risks

The EWG Health Guideline of 0.02 ppb for chromium (hexavalent) was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer.

Pollution Sources

industry icon

Industry

naturally occuring icon

Naturally Occurring

Filtering Options

reverse osmosis icon

Reverse Osmosis

ion exchange icon

Ion Exchange

Dibromochloromethane

Potential Effect: cancer32x EWG'S HEALTH GUIDELINE
THIS UTILITY3.17 ppb
EWG HEALTH GUIDELINE0.1 ppb
NO LEGAL LIMIT
DETAILS
X

Dibromochloromethane

more about
this contaminant

Dibromochloromethane, one of the total trihalomethanes (TTHMs), is formed when chlorine or other disinfectants are used to treat drinking water. Dibromochloromethane and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Click here to read more about disinfection byproducts.

Dibromochloromethane was found at 32 times above EWG's Health Guideline.

EWG Health Guideline

0.1 ppb or less

This Utility

3.17 ppb

National Average

3.42 ppb

State Average

2.61 ppb
NO LEGAL LIMIT
The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2015-2017.
ppb = parts per billion

Health Risks

The EWG Health Guideline of 0.1 ppb for dibromochloromethane was proposed in 2018 by the California Office of Environmental Health Hazard Assessment as a one-in-a-million lifetime risk of cancer. Values greater than one-in-a-million cancer risk level can result in increased cancer cases above one in a million people.

Pollution Sources

water treatment icon

Treatment Byproducts

Filtering Options

carbon filter icon

Activated Carbon

reverse osmosis icon

Reverse Osmosis

Dichloroacetic acid

Potential Effect: cancer18x EWG'S HEALTH GUIDELINE
THIS UTILITY12.7 ppb
EWG HEALTH GUIDELINE0.7 ppb
NO LEGAL LIMIT
DETAILS
X

Dichloroacetic acid

more about
this contaminant

Dichloroacetic acid, one of the group of five haloacetic acids regulated by federal standards, is formed when chlorine or other disinfectants are used to treat drinking water. Haloacetic acids and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Click here to read more about disinfection byproducts.

Dichloroacetic acid was found at 18 times above EWG's Health Guideline.

EWG Health Guideline

0.7 ppb or less

This Utility

12.7 ppb

National Average

7.82 ppb

State Average

12.3 ppb
NO LEGAL LIMIT
The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2015-2017.
ppb = parts per billion

Health Risks

The EWG Health Guideline of 0.7 ppb for dichloroacetic acid was defined by the Environmental Protection Agency as a one-in-a-million lifetime risk of cancer. Values greater than one-in-a-million cancer risk level can result in increased cancer cases above one in a million people.

Pollution Sources

water treatment icon

Treatment Byproducts

Filtering Options

carbon filter icon

Activated Carbon

reverse osmosis icon

Reverse Osmosis

Nitrate*

Potential Effect: cancer9.1x EWG'S HEALTH GUIDELINE
THIS UTILITY1.27 ppm
EWG HEALTH GUIDELINE0.14 ppm
LEGAL LIMIT10 ppm
DETAILS
X

Nitrate, a fertilizer chemical, frequently contaminates drinking water due to agricultural and urban runoff, and discharges from municipal wastewater treatment plants and septic tanks. Excessive nitrate in water can cause oxygen deprivation in infants and increase the risk of cancer. Click here to read more about nitrate.

Nitrate was found at 9.1 times above EWG's Health Guideline.

EWG Health Guideline

0.14 ppm or less

This Utility

1.27 ppm

Legal Limit

10 ppm

National Average

0.938 ppm

State Average

1.43 ppm
The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2015-2017.
ppm = parts per million

Health Risks

The EWG Health Guideline of 0.14 ppm for nitrate was defined by EWG . This health guideline protects against cancer and harm to fetal growth and development.

Pollution Sources

agriculture icon

Agriculture

urban area icon

Runoff & Sprawl

naturally occuring icon

Naturally Occurring

Filtering Options

reverse osmosis icon

Reverse Osmosis

ion exchange icon

Ion Exchange

Total trihalomethanes (TTHMs)

Potential Effect: cancer269x EWG'S HEALTH GUIDELINE
THIS UTILITY40.3 ppb
EWG HEALTH GUIDELINE0.15 ppb
LEGAL LIMIT80 ppb
DETAILS
X

Total trihalomethanes (TTHMs)

more about
this contaminant

Trihalomethanes are cancer-causing contaminants that form during water treatment with chlorine and other disinfectants. The total trihalomethanes group includes four chemicals: chloroform, bromodichloromethane, dibromochloromethane and bromoform.

Total trihalomethanes (TTHMs) was found at 269 times above EWG's Health Guideline.

EWG Health Guideline

0.15 ppb or less

This Utility

40.3 ppb

Legal Limit

80 ppb

National Average

30.1 ppb

State Average

37.7 ppb
The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2015-2017.
ppb = parts per billion

Health Risks

The health guideline of 0.15 parts per billion, or ppb, for the group of four trihalomethanes, or THM4/TTHM, was defined in a peer-reviewed scientific study by EWG and represents a one-in-one-million lifetime cancer risk level.

Pollution Sources

water treatment icon

Treatment Byproducts

Filtering Options

carbon filter icon

Activated Carbon

reverse osmosis icon

Reverse Osmosis

Trichloroacetic acid

Potential Effect: cancer24x EWG'S HEALTH GUIDELINE
THIS UTILITY12.1 ppb
EWG HEALTH GUIDELINE0.5 ppb
NO LEGAL LIMIT
DETAILS
X

Trichloroacetic acid

more about
this contaminant

Trichloroacetic acid, one of the group of five haloacetic acids regulated by federal standards, is formed when chlorine or other disinfectants are used to treat drinking water. Haloacetic acids and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Click here to read more about disinfection byproducts.

Trichloroacetic acid was found at 24 times above EWG's Health Guideline.

EWG Health Guideline

0.5 ppb or less

This Utility

12.1 ppb

National Average

6.38 ppb

State Average

11.6 ppb
NO LEGAL LIMIT
The state and national averages were calculated using the averages of the contaminant measurements for each utility in 2015-2017.
ppb = parts per billion

Health Risks

The EWG Health Guideline of 0.5 ppb for trichloroacetic acid was defined by the Environmental Protection Agency as a one-in-a-million lifetime risk of cancer. Values greater than one-in-a-million cancer risk level can result in increased cancer cases above one in a million people.

Pollution Sources

water treatment icon

Treatment Byproducts

Filtering Options

carbon filter icon

Activated Carbon

reverse osmosis icon

Reverse Osmosis

Includes chemicals detected in 2015-2017 for which annual utility averages exceeded an EWG-selected health guideline established by a federal or state public health authority; chemicals detected under the EPA's Unregulated Contaminant Monitoring Rule (UCMR 3) program in 2013 to 2015 (and subsequent testing when available), for which annual utility averages exceeded a health guideline established by a federal or state public health authority.

*This water utility buys or otherwise receives some or all of its finished water from Washington Aqueduct Division. Tap water results marked with an * are from the supplying utility.


Other Contaminants Tested


D.C. Water and Sewer Authority compliance with legally mandated federal standards:

  • From April 2016 to March 2019, D.C. Water and Sewer Authority complied with health-based drinking water standards.

Information in this section on D.C. Water and Sewer Authority comes from the U.S. EPA Enforcement and Compliance History Online database (ECHO).

LEARN MORE ABOUT THIS UTILITY

Water Filters That Can Reduce Contaminant Levels

ContaminantActivated Carbonactivated carbonReverse Osmosisreverse osmosisIon Exchangeion exchange
CONTAMINANTS ABOVE
HEALTH GUIDELINES
Arsenic
Bromodichloromethane
Chloroform
Chromium (hexavalent)
Dibromochloromethane
Dichloroacetic acid
Nitrate
Total trihalomethanes (TTHMs)
Trichloroacetic acid
OTHER CONTAMINANTS
DETECTED
Aluminum
Antimony
Atrazine
Barium
Bromochloroacetic acid
Bromoform
Caffeine
Chlorate
Cyanide
Dalapon
DCPA mono- and di-acid degradates
Dibromoacetic acid
Fluoride
Haloacetic acids (HAA5)
Lithium
Manganese
Metolachlor
Molybdenum
Monobromoacetic acid
Monochloroacetic acid
N-Nitrosodi-N-butylamine
N-Nitrosodimethylamine (NDMA)
Perchlorate
Simazine
Strontium
Thorium
Vanadium

Take Action

Contact Your Local Official

One of the best ways to push for cleaner water is to hold accountable the elected officials who have a say in water quality – from city hall and the state legislature to Congress all the way to the Oval Office – by asking questions and demanding answers.

LEARN MORE

Filter Out Contaminants

Check out our recommendations for filters to protect your water against the detected contaminants.

EWG’S WATER FILTER GUIDE