Skip to main content

You make this possible. Support our independent, nonprofit newsroom today.

Give Now

Sewer water will soon heat buildings in South Lake Union. It (allegedly) won’t smell

caption: County Executive Dow Constantine, second from left, toured the site in South Lake Union where wastewater will soon be used to heat several commercial buildings.
Enlarge Icon
County Executive Dow Constantine, second from left, toured the site in South Lake Union where wastewater will soon be used to heat several commercial buildings.
Courtesy of Wastewater Treatment Division

Wastewater will soon be heating five large buildings along South Lake Union’s Dexter Street and Mercer Street, as part of a new pilot program in King County. But don't worry, you won't smell the difference.

King County’s wastewater runs through underground pipes between 65 to 70 degrees. The buildings will tap into the county’s sewage pipes, and filter out solid waste. Then the warm filtered sewage pipes will be lined up next to clean water pipes so it can transfer the heat.

Since the two pipes of water are separated, there is no risk of cross contamination. That’s why the building will not smell, even if a pipe leaks.

You can take a virtual tour here.

There are a total of three slots in this pilot program. Alexandria Real Estate Equities is the first company to pair up with the county. The company says with this new heating technology they expect to reduce their emissions by 99%.

Ericka Kinno with King County said this heating system is essential to cutting down emissions.

“It's an opportunity, in some ways, even an obligation to use this renewable energy resource that we're essentially sitting on that is available to our community,” Kinno said.

Kinno said that the private developer is responsible for designing, constructing, operating, and maintaining the system. Therefore the cost to implement the technology will vary on the size and equipment that is used by the developer. They are also responsible for the price tag.

“It’s a large capital cost up front," Kinno said. "But, the idea is that, over time, it more than pays for itself.”

The pilot program is geared toward bigger commercial buildings, multifamily projects, and large campuses like the one Alexandria Real Estate Equities is building. Kinno said that there are examples of the sewer heat recovery technology “being used in residential communities in other parts of the world.”

The program uses the county’s sewage, but Kinno added that a building can “recapture the heat that is generated within your own building.”

This option is more accessible than tapping into the county’s sewage system.

A total of five Alexandria Real Estate Equities’s buildings are participating in the pilot program. They are located on 701 Dexter Avenue North, 601 Dexter Avenue North, 400 Dexter Avenue North, and 800 Mercer Street.

The new heating system is expected to be active in 2025.

Why you can trust KUOW