Side Sewer Permits

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 located outside the building footprint (except the foundation drains) up to, but not including, the tee, wye, or connection to the public main.

Piping inside your building is considered plumbing and is regulated, permitted, and inspected by Seattle-King County Public Health.

For foundation drains, only the hard pipe portion that connects the perforated footing drain pipe to the drainage system is a side sewer.

Learn more about your Side Sewer. 

A separate, additional permit from the Seattle Department of Transportation (SDOT) is also required if there is any work in the public right-of-way such as equipment staging or excavation.  Visit Seattle Department of Transportation’s Side Sewer FAQs for more information.

• Side Sewer Permit for Repair – required anytime there is a pipe or an external sewer fixture (clean out, yard drain, etc.) that needs to be repaired or replaced. SPU does not require a site plan for a routine repair to an existing private side sewer system.
• Side Sewer Permit for Addition or Alteration – required anytime you need an addition and/or alteration to the existing sanitary or drainage side sewer connection. This work may or may not be associated with a construction or grading permit. Examples include adding a catch basin to an existing drainage side sewer or extending a sanitary side sewer to a new building addition.
• Side Sewer Permit for New Construction – required when you need side sewer work that is associated with an approved construction permit.  Recorded legal documents are often required for new construction and are required to be submitted with the permit application.  More information about legal documents can be found on the Documents, Definitions and Resources page.  SPU cannot issue side sewer permits for new construction until the associated construction permit has been issued.  

For new construction, the side sewer permit includes inspections of drainage and sanitary side sewers.  Both sanitary and drainage side sewers are included on the same permit application.   Any required onsite drainage control facilities are inspected under the side sewer permit. 

•  Side Sewer Permit for Dewatering – typically required when a large project will discharge groundwater to a public combined sewer main
• Side Sewer Capping Permit –  side sewer capping permits are a stand-alone permit typically associated with a demolition permit
• Side Sewer Permit for a Temporary Connection –  required for temporary connections to the City sewer system.  A Temporary Sewer Connection Agreement is required (SMC 21.16.110). 

Side sewer permit fees vary based on the scope of work. 

• A sanitary repair permit for work on private property generally costs $280 (includes one to two inspections)
• A drainage repair permit for work on private property generally costs $375 (includes one to two inspections)
• An addition/alteration permit generally costs $375 (includes one to two inspections)
• A new construction permit costs $375 each for sanitary and storm ($750 total), plus fees for any required recording documents (includes one to four inspections)
• Core tap and core tap inspection fees are part of your permit costs. See SPU Director's Rule FIN-220.2, Development Charges for current fees.

We bill additional inspections at an hourly rate. For more information on fees, see the list of fees by category.

Contact SDOT for questions related to SDOT side sewer permit fees.

• We will process side sewer repair and additions/alterations permits by the end of the next business day after application receipt
• We will process side sewer permits associated with new construction permits within three business days from the time of receipt of a complete application.  Avoid processing delays: include the related construction permit number in the application, and make sure it is issued. Legal documents may be required.  Contact SideSewerInfo@seattle.gov with questions about required documents.
• Please make sure your information is complete and correct to avoid processing delays. If requests for additional information are not responded to in a timely manner, your permit application may be cancelled.

You may extend the permit by sending a request to SideSewerInfo@seattle.gov either prior to the permit expiration date or after the permit has expired. If you don’t renew your permit, SPU will not conduct any additional inspections. This may delay the final approval of other related permits you may have, including construction permits, and may potentially result in an enforcement action.

Information about side sewer design and construction requirements is part of the Seattle Side Sewer Code (Seattle Municipal Code (SMC) Ch. 21.16) and SPU Director’s Rule (DR) 2011-004, Requirements for Design & Construction of Side Sewers (Drainage & Wastewater Discharges).

See Director's Rule 2011-004, "Requirements for Design and Construction of Side Sewers (Drainage and Wastewater Discharges)" for more information on construction requirements.

For sewer only: all new pipe that is greater than 10’ in length must be pressure tested. This is done by either a water pressure test, with a hydrostatic head of 6’ above the crown of the pipe at the upper end of the test section, OR by filling the line with 3.5 psi of air (per City of Seattle Standard Specifications 7-17.3(4) B, Exfiltration Test). The line shall be under test when the inspector arrives and needs to hold for a minimum of 10 minutes to show no leakage.

Yes, 90-degree bends and/or tees are not allowed. All changes in grade or line shall be made with 45 degree or 22 ½ degree bends or wyes. The maximum deflection of two adjacent fittings shall not exceed 45 degrees unless the adjacent fittings are spanned by straight pipe of 2 feet or more.

The City of Seattle will inspect the connection tightline from the footing drains to a drainage side sewer. The perforated footing drain pipe is not inspected. If your project has geotechnical special inspections, your geotechnical special inspector must inspect the footing drains prior to cover. The City of Seattle will inspect the discharge point of connection. Footing drains cannot be day-lighted to the ROW.

• For storm or sewer on private property serving one unit, 4-inch is the minimum size allowed
• For storm or sewer in the public right of way or for a sewer serving two or more units, 6-inch is the minimum size allowed
• For storm or sewer serving a commercial or industrial site, 6-inch is the minimum size allowed

There are two pipe products that are most commonly available

• If you will have greater than 18” of cover over the pipe as measured from the crown of the pipe, PVC pipe – ASTM D 3034 SDR 35 is acceptable
• If you will have less than 18” of cover over the pipe as measured from the crown of the pipe, PVC pipe schedule 40 – ASTM D 1785 with fittings per ASTM D 2466 and D 2467 is acceptable

PLEASE NOTE: This is a solid wall pipe, also referred to as “well casing.”  Cellular core pipe is NOT acceptable.

Bedding is required for the pipe materials (listed above) for both storm and sewer. The pipe must be bedded to the springline (half-way up the pipe) in 5/8” crushed rock (Type 22). This is an angular gravel without fines. The pipe needs to be bedded at the time of the inspection. Pea gravel is not acceptable for bedding PVC pipe.