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During construction, workers may pump groundwater or stormwater away from the site. This process is called dewatering.

Typically, this water is treated and sent to a surface water body, either directly or through a storm drain. If the treated water does not meet water quality criteria; or if direct or indirect discharge is not available, it may be possible to send the treated water to the sanitary sewer. However, you must get permission from your local sewer agency first prior to submitting your complete application to King County Industrial Waste.

  • For City of Seattle, please contact Seattle Department of Construction and Inspections (SDCI) for approval to discharge to the sanitary sewer (you will need: discharge location, flow rate (in gpm), other conditions for discharge to their system, and contact information for who you worked with at the agency) at or 206-684-5362
  • For other local sewer agencies, visit the local sewer agencies webpage for contact information

KCIW will not process your application if it is missing local sewer agency discharge approval information.

We know that the industrial waste authorization and application process is complex. Please contact us if you have questions and our staff will be happy to assist you. If you have difficulty viewing or downloading documents, please visit Software Help.

Who needs formal authorization from King County?

Authorization not required  Authorization required
(see process below)
  • Single family residential construction projects should check with the local city or sewer agency. (For City of Seattle, contact SDCI Side Sewer & Drainage Counter at or 206-684-5362.) KCIW does not require applications from these projects.
  • Projects discharging to separated storm sewers or surface water bodies do not need approval from wastewater utilities. Check with the appropriate entity:
Site characteristics Agency to contact
Contaminated site, any size Washington State Department of Ecology
Clean site, bigger than one acre Washington State Department of Ecology
Clean site, less than one acre Local jurisdiction's storm water utility
Most construction projects discharging to sanitary sewers in King County’s Wastewater Service area (including combined sewers that carry stormwater and sewage in the older parts of Seattle) need approval.

How to get formal authorization

  1. Contact your local sewer agency for permission to discharge to the local sanitary sewer system and confirm they accept water from construction sites. You must obtain the following from your local sewer agency before submitting your application to KCIW:
    • a discharge location,
    • acceptable flowrate (in gpm),
    • other conditions for discharge to their system, and
    • the contact name and phone number of the person providing the above information.

    Local sewer agency contact information:
  2. Once you have the above information, select your King County construction dewatering application (general or individual).
  3. Download, complete, print and sign your application. Scan your signed application and submit it to King County via email:

NOTE: If the proposed dewatering discharges directly to a King County sewer, you will also need to get approval from the King County Local Public Agency (LPA) Program to use the facility for the discharge.

Allow enough time! The General Authorization Process may be complete as quickly as 3-10 working days. The Individual Authorization Process takes about 1 to 3 months depending on the complexity of the project. The cost of General Authorization is a set fee. The cost of Individual Authorization or permit depends on project complexity. This fee is not refundable and must be paid even if your project plans change and you no longer want to discharge to the sewer system. Click here for information about fees.

Select your King County application

KCIW offers two types of authorizations for discharging construction water to sanitary sewers:

General Authorization Application Individual Authorization Application

You may be able to use the General Authorization Application for Construction Dewatering if your project meets all of the following criteria:

  • Site is not contaminated.
  • Site is less than 1 acre.
  • Project will discharge less than 25,000 gallons per day (gpd) to the sanitary sewer.
  • Site has a sedimentation tank.

Applying for a General Authorization is easier and requires less documentation (no exhibits) than an Individual Authorization, and no reporting is necessary once the General Authorization is approved.

If your project does not meet all four criteria, you must use the Individual Authorization Application for Construction Dewatering .

Select your application decision chart


Your permit or letter of authorization to discharge wastewater into the sewer system may require self-monitoring. View and download the self-reporting forms.

The General Construction Dewatering Authorization does not require reporting.

General Construction Dewatering Authorization Process

  • Takes less documentation and less time
  • Has no required exhibits
  • Has no reporting requirements


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