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Public Health - Seattle & King County

Lists of septic professionals

Only individuals with Certificates of Competency or licenses are authorized to perform work and maintenance on septic systems. Contact one of the following septic professionals for any work that needs to be done on your septic system. Also read tips below for questions to ask your septic professional.

  • On-site Wastewater Treatment System Designer or Professional Engineer (Agricultural, Civil or Sanitary)
    Washington State Department of Licensing (DOL) administers licenses for designers and professional engineers. You can find them in the yellow pages or you may find out if the designer or professional engineer has their license by doing a license search on DOL's website as follows:
    • Click here for the DOL license search engine.
    • In the "Profession" drop-down menu, select "Onsite Wastewater Treatment Systems"
    • In the "County" drop-down menu, select "King"
    • Press the 'Search Now' button and it will generate a list of licensed professionals in King County

      NOTE: Engineers who design septic systems may be under the category "Agricultural," "Civil," or "Sanitary."

  • Master Installer

  • Liquid Waste Pumper/Hauler

  • On-site System Maintainer

Questions to ask your septic system professional (it is recommended to contact at least 3 people)

Ask your designer or qualified professional engineer:

  1. What is the price of the following? (some of these services are included in one fee):
    • Preliminary site evaluation
    • Soil log digging
    • Design
    • Stub-out inspection
    • Pressure test
    • Installation inspection
    • Backfill inspection
    • As-built package
  1. Do you charge extra for the Homeowner's manual?
  2. Do you charge for extra visits or consultations?

Ask your master installer:

  1. What is the price of the following?
    • Preliminary evaluation
    • Soil log digging
    • Design for repairs
    • Installation
  1. Does the bid include the County fees?
  2. Do you charge extra for backfill labor?
  3. Is the cost for the backfill material included?
  4. Is the timer (if required) included in the bid?
  5. Do you guarantee your work? Will you complete repairs if there is a problem?

TIP: For a repair, the installer should inspect the property, look at the soil logs, and determine cause of failure PRIOR to any proposals.

Ask your liquid waste pumper/installer:

  1. What is the price of the pump-out?
  2. If the septic tank is over 1,000 gallons, will it cost extra by the gallon?
  3. Does this cost include digging to uncover the septic tank lid(s)? If not, do you charge by the foot? If not by foot, how much do you charge to dig out:
    • 1 septic tank lid
    • 2 septic tank lids
    • Pump tank lid (if you have one)
  1. Does this include dumping fees?
  2. Does this cost include inspection of the inlet and outlet baffles in the septic tank? Do you charge extra to clean the filter baffle?
  3. Is there an additional charge for the extra water and time required to pump a tank that has not been maintained properly (for example, pumped on a regular basis)?
  4. If you have a long distance to pump or will require pumping up a steep slope, provide the distance and elevation to the Pumper. The Pumper will determine whether the truck can provide this type of service.
  5. Do you regularly pump the pump tank? What is the charge for this service? If there is a pump tank, it should be pumped in addition to the septic tank, rinsed with a hose, and pumped dry. If the pump tank is very full, you may be charged an extra fee.