Your Side Sewer

A side sewer carries wastewater from a building's sinks, toilets, and drains to the public sewer in the street.

If you own your home or building, you own your side sewer to the public sewer main. The sewer main is located under a street near your home.

Rendering shows single family home sewer line responsibility, which extends to the sewer mainline.
Graphic shows sewer pipe responsibility, which extends to the sewer mainline.


Side sewers in Seattle are privately-owned and are an important part of the sewer system. Find resources here to help you understand, protect, maintain, and if needed, repair your side sewer.

Sewer guides

SPU’s side sewer program

We can help with:

  • Establishing repair responsibility: Me or SPU?
  • Finding your side sewer’s location on our mapping system
  • Reviewing your side sewer scope video where the connection may be damaged
  • Notifying neighbor(s) about responsibility for repairs on shared side sewers
  • Checking on the status or outcome of a side sewer related request of a SPU work crew
  • Checking to see if we have an inspection video showing the status of your side sewer connection
  • General questions about responsibility for tree roots in your side sewer

Contact us at

Side sewer defects and issues

When you own a home or building, you own the side sewer to the public sewer main. The sewer main is located under a street near the home/building.

Within the City of Seattle, responsibility for maintenance and repair of private side sewers is covered under Seattle Municipal Code Chapter 21.16.

Below please find information to help you understand side sewer defects and issues, including information to help you coordinate with neighbors when you share a side sewer.

Shared side sewers

Sharing a side sewer means that the pipe that leaves your property combines with a pipe from a neighboring property (or properties) before it connects to the public sewer mainline.

From the point that your sewer pipe combines with other properties’ pipes, you and your neighbors share maintenance and repair responsibilities. Seattle Municipal Code Chapter 21.16.030 defines a “Responsible Party” as all of the following persons: (1) Owners, operators, and occupants of property; and (2) Any person causing or contributing to a violation of the provisions of this Chapter 21.16. Joint and Several Liability is defined in Chapter 21.16.354.

Two examples of shared side sewers are shown on the map below.

In this example, the owners for properties A and B share responsibility for the side sewer from where their two pipes meet (indicated by the marker) to the connection with the sewer mainline. Likewise, the owners for properties C and D share responsibility from where their two sections of side sewer meet (see marker) out to the connection with the sewer mainline.

Coordinating side sewer repairs with your neighbors

If your shared side sewer needs repair or maintenance, then we would encourage you and your neighbors to come to an agreement on the scope of repairs required and to also agree on which contractor to use to complete the work. We always recommend that property owners get at least three bids from contractors prior to commencing any repair work.


If you have reviewed this material and have additional questions about your side sewer and shared responsibility, then please email us at

Related programs

Public Utilities

Andrew Lee, General Manager and CEO
Address: 700 5th Avenue, Suite 4900, Seattle, WA, 98104
Mailing Address: PO Box 34018, Seattle, WA, 98124-5177
Phone: (206) 684-3000

Newsletter Updates


Sign up for the latest updates from Public Utilities

Seattle Public Utilities (SPU) is comprised of three major direct-service providing utilities: the Water Utility, the Drainage and Wastewater Utility, and the Solid Waste Utility.