(Washington, D.C.) – The District of Columbia Water and Sewer Authority (DC Water) experienced an unexpected loss of water supply from the Army Corps of Engineers’ Washington Aqueduct, resulting in a loss of pressure in DC Water’s distribution system on Friday, January 19, 2024.

The drop in pressure triggered a Boil Water Advisory which impacted 19,000 customers in Wards 3, 4, and a small portion of Ward 5. U.S. Environmental Protection Agency (EPA) regulations require DC Water to issue a precautionary Boil Water Advisory when system pressure drops below 20 psi.

DC Water purchases drinking water from the Washington Aqueduct and distributes it through 1,300 miles of pipes. The Aqueduct provides all of the treated drinking water that is delivered to customers in the District.

DC Water’s investigation found that the loss of pressure on January 19 was a result of the Aqueduct operating a valve on a bypass service line.

Sequence of Events

• At 11:15 am on January 19, the Aqueduct closed a bypass service valve that feeds water into DC Water’s distribution system, in preparation for a repair.
• Approximately three minutes later, the pressure in DC Water’s distribution system started to drop and DC Water began receiving more than 1,000 reports into the emergency call center of low or no water pressure from customers in the impacted area.
• DC Water dispatched water and pumping operations crews to investigate the pressure loss in the Authority’s distribution system, but they could not locate a significant leak or other potential cause.
• DC Water was able to restore service to customers by 4:15 pm by pumping water into the impacted area from another part of the distribution system.
• In coordination with DC Water, the Aqueduct reopened the bypass valve on Saturday, January 20 and the pressure issue was resolved, allowing DC Water to resume normal operations.

“The operation of the bypass service valve, as well as the resulting pressure loss and Boil Water Advisory had a significant impact on our customers, local businesses and our critical infrastructure,” said DC Water CEO and General Manager David L. Gadis. “It was not the outcome that the Aqueduct or DC Water anticipated - actuating a bypass valve should not have had a detrimental impact on the system – and we will continue to work with the Aqueduct to investigate exactly why that occurred and to ensure it doesn’t happen again.”

The Boil Water Advisory was lifted at 5:00 am, on Sunday, January 21, 2024, after DC Water tested water samples from multiple sites in the affected area and verified that there was no risk of water contamination from the loss of pressure.