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Wastewater Treatment

King County, Washington

For questions about the Wastewater Treatment Division website, please send an e-mail message or contact us at:

King Street Center
201 S. Jackson St., Suite 500
Seattle, WA 98104-3855
Phone: 206-477-5371
Fax: 206-684-1741
Telecommunication device for the deaf (TTY): 711

Get Directions to our office location in Seattle, Washington.

Staff Contacts

Maintain your side sewer

Side sewer problems (root intrusion, cracks, faulty connections)
A side sewer connects the house to the local sewer line in the street. Maintenance of a side sewer is the property owner's responsibility.

Roots in an excavated side sewer
Side sewer blocked by roots -- click to enlarge .

Sewage Overflow Card, front side
Know your sewer system (PDF)

Every property has one sewer pipe that connects the building(s) to the larger sewer and treatment system. Side sewers could be made out of clay, iron, plastic, concrete or brick depending on the age of the home or buildings-- maintenance is the property owners responsibility. Always call before you dig (external)!

To prevent side (lateral) sewer problems know your pipe – where it is located, how old it is and any known tree root problems. Maintain your side sewer by not flushing garbage or rinsing grease down drains, and by planting trees and shrubs with low root damage potential.


  • When buying a new house always get a side sewer inspection.
  • If you are remodeling or landscaping make sure you know where the side sewer is first!
  • Know the 24 hour emergency contact for your local sewer utility for issues with odors or overflows.
  • Know how old your sewer line is and the condition it is in. Plan to have it eventually replaced if it has cracks and leaks. The farther ahead you plan the more options you have for replacement and maintenance and the less chance of an emergency overflow or broken pipe. Check with your local city for permitting questions.

Helpful Hint: Slow drains and/or sewer odors can indicate side sewer problems.

Did you know? Side sewers are often the age of your house and can be made out of clay, brick, concrete, iron or plastic. Tree roots commonly enter sewer pipes and can cause clogs and overflows.

External links

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