DC Water Investigating Sanitary Sewer Overflow from Potomac Interceptor in Maryland

January 19, 2026
Map of the impacted area.

WASHINGTON, DC — DC Water is investigating a Sanitary Sewer Overflow (SSO) from the Potomac Interceptor (PI) sewer line in C & O Canal National Historical Park in Montgomery County, Maryland. Flow was observed coming out of the PI this evening, and DC Water has mobilized its crews and contractors to mitigate the overflow and keep it contained as much as possible so they can assess the damage and begin repairs.

The damaged pipe is close to the Clara Barton Parkway, just east of the 495 interchange, and workers have closed the right inbound lane as a precaution. Drivers should anticipate delays during the morning rush hour and consider alternate routes. Trails and parking areas along the Parkway may also be impacted. 

The overflow is expected to reach the Potomac River. It is important to note that DC Water's drinking water system is separate from the wastewater system and is NOT affected by the overflow. The overflow is downstream from the Washington Aqueduct’s intakes at Great Falls.

The PI carries about 60 million gallons of wastewater daily from areas near Dulles Airport to the Potomac Pumping Station in the District. Flows from the pump station are then sent to the Blue Plains Advanced Wastewater Treatment Plant for treatment.

Untreated sewage can contain many pathogens causing a variety of illnesses ranging from E. coli to hepatitis. If people come in contact with the untreated overflow, they risk getting sick and bringing these pathogens into their homes; and should take the steps below:

  • Leave the area immediately.
  • Wash exposed skin thoroughly with soap and clean water.
  • Disinfect any affected areas or items.
  • Do not consume food or water that may have been exposed.
  • Seek medical attention if symptoms occur.
  • Report exposure to DC Water at (202) 612-3400.

Residents who live near the impacted area may notice an odor from the overflow. Emergency measures will be taken to prevent further spillage. The extent of the repairs and duration are still being determined. 

If you have additional questions or need information you may contact DC Water’s Customer Care team at (202) 354-3600 (Monday-Friday, 8 a.m. to 5 p.m.) or the 24-Hour Command Center at 202-612-3400.

Latest News

Map of lane closure on Clara Barton Parkway at Maryland-DC Border

Drivers should expect delays on Clara Barton Parkway at the Maryland – DC border on Saturday, Sept 26. One lane will be closed from 7 a.m. to 3 p.m. while DC Water makes repairs as part of ongoing ...

Christening of TBM Emily with DC Water Interim General Manager Matt Brown holding bottle of tap water to christen Emily

DC Water celebrated the christening of Emily today. It’s the second giant tunnel boring machine (TBM) that will help build the 5.5-mile Potomac River Tunnel. The celebration continued with Community Day. Residents and families met Emily and stepped inside the tunnel where she will soon begin digging.

Map: Temporary closure of the southbound curb lane on Rock Creek and Potomac Parkway NW

DC CLEAN RIVERS – POTOMAC RIVER TUNNEL PROJECT

Drivers should expect a temporary southbound lane closure on Rock Creek and Potomac Parkway NW between F St and Virginia Ave on Saturday, September 19, and Sunday, September 20, 2026. The closure will be in place from 7 a.m. to 7 p.m. each day, weather permitting.

Upcoming Meeting

Board of Directors Meeting

April 24, 2023

Monday 9:00 AM

Announcement

Christening of TBM Emily with DC Water Interim General Manager Matt Brown holding bottle of tap water to christen Emily
DC Water Welcomes the Community Underground to See the Potomac River Tunnel and Christens Tunnel Boring Machine Emily

DC Water celebrated the christening of Emily today. It’s the second giant tunnel boring machine (TBM) that will help build the 5.5-mile Potomac River Tunnel. The celebration continued with Community Day. Residents and families met Emily and stepped inside the tunnel where she will soon begin digging.

Latest Blog Post
Emergency supplies arranged on a table, including bottled water, canned food, a backpack, first aid kit, flashlight, phone, medication and other essential items.
Simple Ways to Stay Prepared at Home
A few simple steps can help your household prepare for severe weather and temporary water or sewer service interruptions.
Upcoming Meeting
Date
October 8, 2026
Thursday, 9:30 AM

Upcoming Events

Customer Service Center Announcement

Payment Plan Incentive: provides a credit back of 50% of the last 3 payments made. Eligible participants are residential customers who have had an outstanding balance for 60 days or greater and with an outstanding balance of $500 or more.