On January 19, a section of the Potomac Interceptor Pipeline collapsed near the Clara Barton Parkway and the I-495 interchange. The 54-mile sewer pipeline transports wastewater from Northern Virginia and suburban Maryland to the Blue Plains Advanced Wastewater Treatment Plant in Washington, DC.  

The broken pipe, which measured roughly six feet in diameter and is estimated to have an average flow of 40 million gallons of untreated sewage a day, caused an overflow into the C&O Canal National Historical Park, before then entering the Potomac River. 

DC Water, which owns and operates the pipeline, has constructed a bypass pumping system to contain most of the overflow, which is capturing and rerouting wastewater around the collapsed interceptor segment, while repairs proceed. DC Water is also testing the river for E. Coli and reporting results on its website. Officials note that drinking water is safe and not impacted by this incident.  

Rehabilitating the pipeline, which was originally constructed in the early 1960s, is a high priority DC Water project. It is estimated that the rehabilitation project will take about 10 years and cost approximately $625 million.  

March 11, 2026 - COG Board meeting item on pipeline response 

Agenda and presentation from the briefing
 

February 23, 2026 - COG Virtual Regional Briefing for area officials 

Agenda and presentations from the briefing

External Resources

DC Water Potomac Interceptor landing page  

DC Department of Energy and Environment (DOEE)

Maryland Department of the Environment (MDE) 

Virginia Department of Environmental Quality (VDEQ)

Virginia Department of Health (VDH)

Additional Summary Information

DC Water Response to the Collapse

Water Sampling Locations

Advice to the Public

COG Coordination Activities

DC Water Response 

• Has constructed bypass pumping systems to contain most of the overflow. 
• Is capturing and rerouting most of the wastewater with bypass pumping systems around the collapsed interceptor segment during repairs.
• Is monitoring bypass systems 24/7.
• Is conducting daily water quality sampling.
• Has stood up a dedicated DC Water webpage for information on the Potomac Interceptor Collapse. 
• Is developing an Environmental Restoration Plan with federal, state, and local regulators. 

Water Quality Sampling 

• Water quality monitoring partners from DC Water, DC Department of Energy & Environment (DOEE), Maryland Department of the Environment (MDE), Virginia Department of Environmental Quality (VADEQ), and the Potomac Riverkeeper Network with University of Maryland (UMD) have been testing for E. coli, an indicator bacterium, since late January 2026.

• DC Water reports “Overall, results show mostly decreasing trends since the start of sampling.  Although the overflow is now mostly contained, E. coli levels are expected to continue fluctuating over time due to residual impacts from the incident and ongoing influences from weather conditions such as precipitation, snowmelt, temperature variability, and other natural sources of E. coli bacteria such as wildlife.” 
• DOEE created a dashboard that consolidated E. coli testing data from DC Water, DOEE, MDE, VADEQ, and the PRKN/UMD.   

Monitoring Resources

• DC Department of Energy and Environment FAQ (DOEE)
• DC Water Potomac Interceptor landing page  
• Maryland Department of the Environment (MDE) 
• Virginia Department of Environmental Quality (VDEQ)
• Virginia Department of Health (VDH)

 

Advice to the Public 

Area environmental and health officials note that the pipeline collapse has had no impact on the region’s drinking water. All active drinking water intakes are located upstream of the collapse site. Regional drinking water utilities treat Potomac River water through filtration and disinfection processes before distribution. 

(Update: March 5, 2026) The Maryland Department of Health announced Charles and Prince George’s counties have lifted the recreational water advisories in effect from late January. Montgomery County’s advisory will remain in effect until further notice. There continues to be no recreational water advisory necessary for the Potomac River in St. Mary’s County.

The Virginia Department of Health (VDH) announced it is partially lifting the recreational water advisory for the portion of the Potomac River from the Route 120 Chain Bridge to the Governor Harry W. Nice Memorial Bridge (Route 301) in King George County. The advisory remains in place upstream, from the American Legion Memorial Bridge (I-495) to the Route 120 Chain Bridge.

The District Department of Health (DC Health) has lifted the recreational advisory for the Potomac River in Washington, DC stating that consistent water quality testing shows bacterial levels are now within safe ranges for recreation. The advisory applies only to waters within the District of Columbia. 

The region’s water utilities encourage residents to avoid flushing ANY wipes or non‑disposable items, as these materials can interfere with pumping operations during emergency response and repair activities. 

Residents can also report suspected fish and wildlife injuries related to the incident to the District or Maryland.  

COG Coordination Activities 

COG is working with its member governments and partners on the following coordination activities to support the region’s response to the sewer pipeline collapse.  

• Providing briefings and updates across jurisdictions, including planning the first regional briefing of officials from the District, Maryland, and Virginia.  
• Aligning and amplifying messaging across jurisdictions (e.g., safe drinking water, health advisories, wipes guidance, and PI resilience investments);  
• Coordinating water quality monitoring activities across jurisdictions (e.g., state and local governments, University of Maryland)