Side sewer repair in Seattle: costs, permits and repair methods

What is a side sewer, and who is responsible for it?

A side sewer is the private pipe that carries wastewater from a building's sinks, toilets and drains to the public sewer. Other cities call it a sewer lateral. Seattle Public Utilities is clear about ownership: the entire side sewer, all the way to the connection to the public main, is owned and maintained by the property owner. It includes all piping outside the building footprint up to, but not including, the tee, wye or connection at the main. That means the owner is also responsible for the part under the sidewalk and street.

Piping inside the building is plumbing and is permitted and inspected by Public Health Seattle and King County. SPU repairs the public mainline. Some properties share a side sewer, and some have a backwater valve, which SPU says the owner must maintain. SPU's side sewer maintenance page suggests starting by downloading your property's side sewer information from the Seattle Department of Construction and Inspections website, so you know where the pipe runs.

What does side sewer repair cost?

SPU adds that repairs requiring digging in the public right-of-way cost more, and a separate Seattle Department of Transportation permit is needed for any work in the street, including equipment staging or excavation.

Which side sewer defects need repair?

SPU's defects guide grades common camera findings so you can judge a contractor's recommendation:

• Offset joints. Minor offsets need no repair, moderate ones should be reinspected after a few years, and severe offsets that let soil erode into the pipe should be repaired.
• Sags. Side sewers are built at a slope of a quarter inch per foot. SPU calls a sag under 25 percent of the pipe diameter minor, 25 to 50 percent moderate (inspect every two to five years), and 50 percent or more a repair item.
• Cracks and fractures. Minor ones are reinspected in three to five years, moderate ones every one to two years, and severe ones near collapse need repair.
• Holes. SPU recommends repair for holes of every size, because they can wash soil away and leave voids that may become sinkholes.
• Roots. Older concrete and clay pipes without watertight joints are especially at risk.

Spot repair, open cut, pipe bursting or lining?

SPU's repair methods page describes four approaches, sometimes combined:

• Spot repair: a hole is dug to replace one section where there is an offset, a collapse or roots that cannot be removed another way.
• Open cut: the old pipe is dug up and replaced, used when many sections are defective. It disturbs the most surface.
• Pipe bursting: a new pipe is pulled through the old one, with a pit at each end.
• Cured-in-place pipe (CIPP) lining: a resin-soaked liner is inflated inside the old pipe and hardens into a seamless pipe within a pipe, which SPU says can keep roots out.

What permits and inspections apply in Seattle?

SPU says permits are always required, on private property and in the right-of-way, when performing repair work on side sewers. They are not required for root removal or unclogging. SPU processes repair permits by the end of the next business day, permits are valid for 18 months, and your contractor schedules a city inspection before the pipe is covered, followed by a final inspection. New pipe longer than 10 feet must pass a pressure test. Design and construction rules are in the Seattle Side Sewer Code, SMC chapter 21.16.

How do you choose a side sewer contractor?

• Get at least three written bids; SPU recommends this because prices vary widely.
• Ask each bidder for the cause, the footage of the defect and the repair method, in writing, signed and dated, and for a copy of the inspection video.
• Confirm the company in the L&I verify tool. SPU's side sewer guide says repairs in the city right-of-way must be done by a contractor licensed to work in Seattle and backed by a contractor bond.
• Ask who applies for the SPU permit and the SDOT street permit, and how restoration of the sidewalk or yard is priced.

Low- to moderate-income owners of single-family homes can ask the Seattle Office of Housing about its Home Repair Loans, which SPU mentions on its repair page. For a deeper comparison of methods, see side sewer repair options in Seattle.

We are an independent guide and do not do this work. You can send a request through our contact page; we reply with next steps and, where we know a licensed contractor for your area, an introduction.