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Plumbing can be difficult. Public Health - Seattle & King County recommends you hire a professional plumber. If you choose to do your own plumbing, please adhere closely to the following instructions.

When a permit is required

Whenever you are going to install, relocate or change a plumbing system, Seattle and King County plumbing codes require that you obtain a permit. Public Health - Seattle & King County has jurisdiction in Seattle and unincorportated King County.

For homeowners only

The permit issued to a homeowner is an authorization for the homeowner to do the plumbing work or to receive assistance from a friend, neighbor, relative or other person when none of the individuals doing such plumbing hold themselves out as engaged in the trade or business of plumbing. (See RCW 18.106.150) If you are being authorized by the property owner to apply for the plumbing permit, your signature on the permit application signifies that you have such authorization from the owner of the property. If a professional plumber is contracted with, they must be a registered contractor per Chapter 18.27 RCW.

Why permits are necessary

Plumbing systems carry drinking water and wastewater. If the wastewater mixes with the drinking water, there is a chance people using that system could get sick. A plumbing system built according to the plumbing code is a safe system.

How the plumbing inspectors can help the homeowner

Important: The following is a service provided to all installers, but may be especially useful to homeowners performing their own design and installation. Once you have obtained the plumbing permit, you have the option to submit an industry standard drawing (isometric or elevation) of the plumbing system you want to install in your home. This drawing should include:

  • the type of material (copper, ABS, etc.) to be used;
  • the size of each section of piping;
  • the type of each fitting to be used in the waste and vent system; and
  • the sizing of each section of piping for both the hot and the cold distribution lines.

Additional information is available from our Plumbing and Gas Piping homepage and in-person in print format at our Seattle and Bellevue offices. These will provide further guidance in designing your plumbing system. Home improvement stores and or hardware stores sell do-it-yourself publications that may also be helpful.

You may contact your plumbing inspector between 7:00 am and 8:00 am for a brief consultation about your project or you can leave a message on the inspector's voicemail for a return call on the next working day. The inspector will discuss the options available to you, such as faxing the drawing to the inspector or scheduling an appointment to meet the inspector at the office.

If you choose to do your own plumbing installation as outlined in this guideline, it is your responsibility to design your system. The plumbing inspectors are not authorized to design the system for you. They can provide information regarding application of the plumbing code or assist you in understanding the department handouts available to you. If you need assistance designing your plumbing system, we recommend that you contact a professional plumber.

Buying your permit

In order to get the permit, you will need to know the parcel number (tax ID number). This number can be found on your tax records, your building permit, or you may obtain it by calling the King County Assessor's Office.

Permit fees

Permit expiration

Your plumbing permit will expire one year from the date on which you purchased it. You have the option to renew the permit for $50.00 or 1/2 of the original permit fee, whichever is less.

Installation and inspections

The permit must be purchased and posted at your job site before you start installing the plumbing system. The approved construction plans must also be on site. Note: All work must be approved by the plumbing inspector before you cover it up.

List of steps

  1. Test the plumbing system for leaks. Test the drain, waste and vent systems and the water distribution system. The inspector neither performs nor provides the means for conducting the test of the plumbing system.

    To test the drain, waste and vent system, make sure that all pipes and fittings are properly glued. Plug all openings tightly and look the system over carefully to make sure all is ready for the test. Fill the system with water to the roof (or at least 10-feet high for a groundwork) and check the entire system for leaks.

    To test the water distribution system, make sure the system is completed and ready to hold pressure. Connect the system to the water source of the building so that the system will be tested with the water pressure that will exist in the system under normal operating conditions. Check the entire system for leaks.

    The drain, waste and vent system and the water distribution system must be under test and not showing any sign of leakage at the time of inspection.

  2. The "groundwork" inspection. Plumbing systems installed below ground, such as under a concrete floor that needs to be poured before continuing construction, must be tested and inspected prior to cover. Call the inspection line to request a groundwork inspection. Do not cover any of the pipes before the inspector approves the work.

  3. The "rough-in" inspection. This will be an inspection of the entire plumbing system that will be concealed within the construction of the walls, floors or ceilings. Call the inspection request line to request a rough-in inspection. Again, the inspector needs to see all of the system, so do not cover any part of the system prior to inspection.

    Note: This inspection must be completed and approved prior to contacting the building inspector for your framing inspection.

  4. The "final" inspection. When the fixtures are installed and operational, you must call the inspection request line and request a final inspection. Although the system will be operational, remember that the system is not approved for normal use until final approval.

    Note: This inspection must be completed and approved prior to contacting the building inspector for your final building/occupancy inspection.

Request an inspection

Call the inspection request line at 206-205-0935. Inspections called in after 6:00 AM will be placed on the next working day's inspection list. Same day inspections cannot be guaranteed and specific appointment times cannot be made due to large inspection workloads and geographical areas, but a sincere effort will be made to serve you quickly. When phoning the inspection request line, be sure to leave the following information in your inspection request:

  • Your name
  • The plumbing permit number
  • The address of the project
  • The type of inspection being requested
  • Any additional information the inspector may need to find your job site