Boil Water Advisory lifted in DC and Arlington as water quality confirmed safe

All D.C. and Arlington County residents under the precautionary boil water advisory can now use tap water for all purposes, following confirmation that the drinking water from the Washington Aqueduct never deviated from U.S. EPA-established water quality standards.

The advisory was issued Wednesday by DC Water on the advice of the Washington Aqueduct as a conservative measure to protect public health. 

"We sincerely appreciate our customers’ patience while we took necessary precautions to ensure the safety of the tap water we deliver," DC Water stated Thursday morning. 

The advisory affected all customers in the District of Columbia, including the Pentagon, Arlington National Cemetery, and Reagan National Airport. Arlington County customers were also impacted.

DC Water will continue to work with customers to answer questions and address any issues following the Boil Water Advisory.

Upon observing the increase in algae and resulting turbidity on Wednesday, Washington Aqueduct staff implemented additional mechanical and chemical treatment solutions to meet system water supply demands and EPA standards. 

The US Army Corps of Engineers said that staff immediately began washing filters to increase production and made necessary chemical adjustments, including increasing coagulants that prevent filter clogs. Alternate filters were also brought online for additional treatment capacity.

Additionally, the EPA authorized the addition of copper sulfate and sodium permanganate to combat algae in the Washington Aqueduct’s reservoirs.

The Aqueduct, which sources its water from the Potomac River, serves the District of Columbia and Arlington County. 

Higher levels of turbidity can affect the effectiveness of the water treatment process.