Wastewater/Sewer

Wastewater Pump Station 1Overview

The City of Redmond Wastewater Maintenance Division maintains and operates the wastewater (sewer) system to meet the needs of existing and future customers. The wastewater system serves a residential population of 69,900 (2020) within the City limits and approximately 3,500 residential households in the Novelty Hill area.

City staff maintain the wastewater system in a manner that protects the public investment, protects the environment and human health, ensures compliance with state and federal mandates, and ensures that reliable service is available to all customers of the City utility system.

Wastewater staff provide information to commercial customers and residents about the treatment and reduction of grease and industrial discharges to the wastewater system to ensure compliance with pre-treatment standards. Wastewater Division staff also collaborate with Utility Engineering staff on long-range system development and comprehensive planning, the capital facility program, and feasibility studies.

  1. Lift Station Program
  2. Maintenance & Repair
  3. Technology

What: Replace or rehabilitate ten wastewater lift stations in six years. At the start of the program, the Sewer Utility owned and operated 23 lift stations throughout its service area (see map for locations; stations identified for replacement are numbered). With the completion of the Lift Station 14 abandonment project, there are now 22 wastewater lift stations.

When: Now–2022

Why: If a lift station fails there is a risk that raw sewage will back up into homes or businesses, or overflow into Lake Sammamish and other natural waterways. Ten wastewater lift stations are at, or past, their useful life. Mechanical and electrical equipment in lift stations usually lasts 20-30 years. Some of the lift stations are over 30 years old, some are failing now, and some have equipment for which replacement parts are no longer available.

How: The sewer lift stations will be replaced or rehabilitated using sewer rates, development connection charges, and bonded debt so that the stations are in good working order by 2025.

Progress: In 2019, Lift Station 2 was replaced and Lift Station 14 was abandoned and a new sewer line installed. Lift Station 3 was replaced in 2020. Lift Station 13 work started in 2020 and is expected to be complete in 2021. Also in 2021, work on Lift Station 12 started. Five lift stations are currently in design for targeted equipment upgrades in 2022.

What is a lift station?

Due to hills and valleys in the landscape, sewer systems include locations where sewage needs to be pumped from low points to higher elevations, from which it will ultimately flow via gravity to a King County treatment plant. Once sewage arrives at the treatment plant it is treated and discharged to Puget Sound.

Septic Systems

Septic system postcard

Septic system owners need to regularly inspect and maintain their septic system (including repairs and replacements as their septic system ages). If septic systems are not properly maintained, they no longer receive their benefits. Instead, they can harm groundwater and pollute lakes, streams, and beaches. They can even cause sewage to surface in your yard or back up into your house. To prevent this, a septic system owner also needs to operate their system properly, such as throwing all food waste into the compost or trash can instead of tossing it down the drain (see more at Taking care of your septic system - King County).

For Additional Septic Information
Visit the King County Sewer System page, On-site Sewage System (OSS) Program - King County.


3 Steps to Lengthen the Life of Your Septic System

  1. Pump Your Septic Tank
    1. Septic Tanks are typically pumped every 3 to 5 years, depending on water use. Generally, septic tanks accommodating larger households will need to be pumped more frequently.
  2. Check for Septic System Failure
    1. Call your septic system professional if you experience any of these indicators of septic system failure:
      1. Odor
      2. Wet spots or standing water near the septic tank or drain field
      3. Backups in toilets, drains, or sinks
      4. Bathtubs, showers, and sinks drain very slowly
  3. Regularly Inspect Your System
    1. Contact a certified septic system professional to inspect and monitor your system with the following recommended frequency: 
      1. Gravity systems: Every three years
      2. Pressure distribution systems: Annually
      3. A proprietary system such as an aerobic treatment unit (ATU), membrane bioreactor
      4. (MBR), drip irrigation, and other products:
      5. Annually, or more often if required by the manufacturer
      6. Mound or sand filter systems: Annually

Find a Certified Septic System Professional

Visit the King County Site to search for certified septic system professionals: King County list of on-site sewage system professionals.