Sewer System Improvements

Our Blue Plains Advanced Wastewater Treatment Plant has an outstanding reputation, as a result of our compliance with environmental regulations and our advanced methods of wastewater treatment. Although the technology and facilities at Blue Plains are up-to-date, the sewer infrastructure that feeds the DC Water service area is aging and requires updates and improvements.

To make the sewer system more effective in protecting the environment, we are making significant structural improvements that will reduce sewer overflows and improve the health of our waterways.

In the District of Columbia, most of the sewer system includes one pipe for carrying wastewater from homes and businesses to the Blue Plains treatment plant, and another pipe that carries storm water runoff to area waterways. But approximately one-third of the region has older sewer systems that contain a single pipe that carries both wastewater and storm water runoff. These single pipes are called combined sewer systems, or CSS.

When it rains heavily in areas served by a combined sewer system, the storm water and wastewater flow through the same pipe. Some of the pipes aren't big enough to handle the flows of very large rainstorms. Rather than have the combined water back up into homes and streets, the combined sewer system sends the overflow water to the local waterways. The result is called a combined sewer overflow, or CSO.

To improve the health of our waterways, we've implemented a large-scale, long-term plan to reduce CSOs in local waterways. We will separate the sewer pipes and eliminate several CSO outfalls (places where water is discharged into waterways) and use the outfalls for storm water only.

Sewer separation will benefit the region by:

  • Improving the quality of life for the community
  • Producing a positive impact on the environment
  • Supporting future development

New stormwater outfalls will be created on both the Anacostia and Potomac Rivers. We will begin work on the Anacostia River first, because it is a slower-moving river, and pollution stays longer and does more damage in rivers with a slow current.

By the year 2025, we expect to reduce CSOs in the Potomac and Anacostia rivers and Rock Creek by 96% overall. CSOs in the Anacostia will be reduced by 98%.

More information on the Clean Rivers Project.