The City's wastewater system is separated into collection and treatment. The collection system is maintained by the City Street Division. Treatment is managed under a contract with Jacobs.


Sewer Backup Information

To report a sewer backup during normal business hours, please contact the Street Division office. If this is an emergency after hours, please call the after hours non-emergency number. Learn more about clean up of a sewer backup and the claim process.


Contact the Street Division to Report...

  • Wastewater overflows
  • Missing, overflowing or rattling manhole covers
  • Sewer odor in your home or outside of your home
  • Verification of whether you are connected to the City sewer or a septic tank

To request a new connection to the City's sewer system and applicable permit information, contact Development Services.

The Wastewater Treatment Plant and six lift stations throughout Walla Walla are managed and operated by Jacobs. The City of Walla Walla and Jacob's partnership has been in effect since April 2000. The Wastewater Treatment Plant is regulated by the Washington State Department of Ecology's National Pollutant Discharge Elimination System Permit, Environmental Protection Agency, Washington State Department of Health, and Walla Walla City-County Health Department.


The City's Wastewater Treatment Plant is...

  • Designed to treat up to 9.6 million gallons per day (MGD) with the ability to handle an instantaneous peak of 20.0 MGD.
  • The plant currently processes about four to eight million gallons of wastewater per day.
  • As per a 1927 court decree, the Wastewater Treatment Plant discharges treated water to Mill Creek from December 1 through May 1 of each year; it discharges to Blalock and Gose Irrigation Districts the remaining seven months unless the irrigation districts request more.
  • Wastewater treatment is a biological process. Never dispose any of the following down your (street) storm drain or sewer (toilet, sink or any drain in the house) to the wastewater/sewer system:
    • Pharmaceuticals
    • Excessive amounts of bath or body oils
    • Water softener backwash
    • Household cleaners, especially floor wax and rug cleaners
    • Chlorine bleach, chlorides, and pool or spa products
    • Pesticides, herbicides, agricultural chemicals, or fertilizer
    • Flammable or toxic products

The Wastewater Treatment Process Consists of...

  • Headworks with bar screens
  • Grit removal
  • Primary clarifier
  • Aeration basins
  • Secondary clarification
  • Sand filtration
  • UV disinfection
  • Industrial Pretreatment Program (IPP)
  • The Industrial Pretreatment Program is managed by Jacobs and oversees the permit of three industries.

Industrial Pretreatment Program (IPP)

The Industrial Pretreatment Program is managed by Jacobs and oversees the permit of three industries.

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