District of Columbia Water and Sewer Authority
| Company type | Public utility authority |
|---|---|
| Industry | Water supply and wastewater treatment |
| Founded | 1996 |
| Headquarters | Washington, D.C. , United States |
Area served | Washington, D.C., Montgomery County (MD), Prince George's County (MD), Fairfax County (VA), Loudoun County (VA) |
Key people | David L. Gadis (President and CEO) |
| Products | Potable water delivery, sewage collection, wastewater treatment |
Number of employees | Approximately 1,000 (2009) |
| Website | www |
The District of Columbia Water and Sewer Authority (DC Water) is responsible for delivering potable water, managing sewage collection, and providing treatment services throughout Washington, D.C. Additionally, the utility offers wholesale wastewater treatment to several adjacent municipalities in Maryland and Virginia and oversees the upkeep of more than 9,000 public fire hydrants within the District.
Formed in 1996 through collaboration between the city and federal governments, DC Water functions as an autonomous agency under the District’s jurisdiction.
Service area
DC Water caters to over 600,000 residents, accommodates 16.6 million visitors annually, and supports 700,000 workers within Washington, D.C. Beyond the District, it provides wholesale wastewater treatment services to approximately 1.6 million individuals residing in Montgomery and Prince George’s counties in Maryland, as well as Fairfax and Loudoun counties in Virginia.
Drinking water
In 1852, Congress authorized the construction of an aqueduct system to supply drinking water drawn from the Potomac River. The Washington Aqueduct was designed and constructed by the U.S. Army Corps of Engineers and commenced full operation in 1864. During the 20th century, filtration facilities were incorporated to enhance water purification standards.
Wastewater treatment
To prevent untreated sewage from contaminating the Potomac and Anacostia Rivers, the District of Columbia commissioned a $4 million sewage treatment facility at Blue Plains in 1938. Initially built to serve a population of 650,000 with a treatment capacity of 100 million gallons daily (mgd), it required expansion as the population rose to 1.5 million by 1943. Secondary treatment processes were introduced in 1959, boosting capacity to 240 mgd. A significant upgrade during the 1970s added advanced wastewater treatment technology, increasing capacity to 300 mgd by 1983. The Blue Plains plant also extends its services to surrounding Maryland and Virginia communities.
Agency reorganization and name change
Originally overseen by the District government, responsibility for drinking water and sewage management was transferred to DC Water in 1996 when it was established as an independent agency by both District and federal authorities. In 2010, DC Water underwent a rebranding initiative under new leadership that introduced a fresh logo and updated color scheme; however, its official name remains the District of Columbia Water and Sewer Authority.
Statistics
- Workforce: Approximately 1,000 employees (FY 2009)
- Coverage area: 725 square miles (1,880 km²)
- Daily drinking water pumped: (FY 2009)
- Drinking water infrastructure
- Pipeline length: 1,300 miles (2,100 km)
- Number of pumping stations: 5
- Reservoir count: 5
- Elevated storage tanks: 3
- Valves in system: 36,000
- Public fire hydrants: Over 9,000
- Sewer system components
- Combined sanitary and stormwater sewers: over
- Flow-monitoring stations: 22
- Wastewater pumping stations: 9 (including Main Pumping Station)
- Blue Plains Advanced Wastewater Treatment Plant
- Recognized as the world’s largest advanced wastewater treatment facility
- Facility area:
- Treatment capacity: per day; peak capacity: per day
Governance
An eleven-member Board of Directors governs DC Water, with representation allocated as follows: six members from the District of Columbia; two members each from Prince George’s County and Montgomery County; and one member representing Fairfax County. All these jurisdictions are parties to the Blue Plains Intermunicipal Agreement, which outlines governance responsibilities, operational management of facilities, allocation of treatment capacity, and financial arrangements.
The Authority independently prepares its budget, which is then incorporated into the District’s overall fiscal plan and submitted annually to Congress for approval.
Since its establishment as an independent authority in 1996, DC Water’s autonomy over financial matters, procurement processes, and personnel has been further solidified by Congress through the District of Columbia Water and Sewer Authority Independence Preservation Act enacted in 2008.
Operations
The President and CEO is responsible for managing daily activities and reports directly to the Board; the current CEO is David L. Gadis.
DC Water obtains its treated drinking water from the Washington Aqueduct, a division of the Army Corps of Engineers, which draws water from the Potomac River at Great Falls and Little Falls. After treatment by the Aqueduct, DC Water distributes this potable water through an extensive network comprising 1,300 miles of pipelines throughout the District.
Furthermore, DC Water oversees a sewer system exceeding 1,800 miles in length and operates the Blue Plains Advanced Wastewater Treatment Plant, which releases treated effluent into the Potomac River near the southern boundary of the District.
Awards
The National Association of Clean Water Agencies (NACWA) honored DC Water with its Research and Technology Award in recognition of in-house advancements related to biosolids management, disposal techniques, and wastewater treatment processes that safeguard aquatic environments globally. This accolade was awarded to DC Water for the second year running in 2010.
In the same year, DC Water also received NACWA’s Platinum Peak Performance Award after securing five consecutive Gold Awards for achieving full compliance with National Pollutant Discharge Elimination System (NPDES) permit requirements, demonstrating outstanding regulatory performance.
Funding
The rates charged for water and sewer services finance both operational expenses and capital investments, including infrastructure renewal and projects mandated by EPA environmental regulations. Although some funding is derived from grants provided under the Clean Water Act and Safe Drinking Water Act, the majority of capital costs are borne by customers through service rates.
Environmental stewardship
At Blue Plains, wastewater is subjected to tertiary (advanced) treatment before being discharged into the Potomac River, adhering strictly to NPDES permit standards. Since the mid-1980s, Blue Plains has significantly reduced phosphorus emissions to support water quality objectives for both the Potomac River and Chesapeake Bay.
Pursuant to the 1987 Chesapeake Bay Agreement, participating Bay states and the District pledged to reduce nitrogen discharges by 40 percent from 1985 levels. Blue Plains was a pioneer in achieving this goal and has consistently surpassed it since implementing Biological Nitrogen Removal (BNR) technology in 2000, reaching a 58 percent nitrogen reduction by fiscal year 2009.
New NPDES permit requirements effective September 2010 mandate lowering nitrogen discharges to no more than 4.7 million pounds annually. To comply with these limits, DC Water is undertaking an approximately $1 billion project at Blue Plains to install enhanced nitrogen removal (ENR) systems.
During fiscal year 2009, DC Water upgraded pumping stations and filtration systems integrated within a centralized process control framework to improve operational effectiveness. Enhancements included converting nitrification reactors to fine bubble diffusion technology, which supports nitrogen reduction efforts while improving energy efficiency.
DC Water operates two skimmer boats that collectively remove over 400 tons of debris each year from the Anacostia and Potomac rivers, thereby contributing to cleaner waterways that are vital for community activities and environmental preservation.
These environmental efforts establish the District as a leader within the Chesapeake Bay watershed. In 2009, the Chesapeake Stormwater Network awarded the District a leading B+ grade on its stormwater management performance scale, surpassing many other municipalities.
DC Water Clean Rivers Initiative
The District of Columbia manages a combined sewer network that spans roughly one-third of the city, originally constructed in the late 1800s to convey both sanitary sewage and stormwater simultaneously. Although this system functions well during dry periods, intense rainfall can overwhelm the pipes, resulting in combined sewer overflows (CSOs) that release untreated waste into nearby water bodies.
By March 2025, DC Water had achieved about a 40% reduction in CSO events through a $140 million investment involving inflatable dams, tide gates, sewer separation projects, and enhancements to pumping stations to boost system capacity.
In 2013, DC Water initiated the $2.99 billion Clean Rivers Initiative, which entails building an 18-mile-long deep tunnel system designed to temporarily store combined sewage during storms for subsequent treatment at the Blue Plains facility. Parts of this tunnel network were operational as of 2025, with full completion anticipated by 2030. This initiative also incorporates green infrastructure strategies and targets a 96% decrease in CSO discharges.
Lead Contamination in Drinking Water
In 2001, lead concentrations in Washington, D.C.’s drinking water reached levels as high as 1,250 parts per billion—exceeding the Environmental Protection Agency’s (EPA) safety threshold of 15 ppb by more than eightyfold. This contamination was traced back to the Washington Aqueduct’s transition from chlorine to monochloramine for water disinfection, which caused corrosion in pipes and dissolved lead-based solder.
To mitigate this problem, orthophosphate was introduced as a corrosion inhibitor, substantially lowering lead leaching into the water supply. By 2017, DC Water confirmed that its drinking water met EPA lead regulatory standards.
See also
- Loudoun County Sanitation Authority
- Washington Suburban Sanitary Commission (WSSC) – provider for Montgomery and Prince George's Counties