The Water Pollution Control PlantWastewater goes down the drains from our homes and businesses, travelling through the City of Thunder Bay sanitary sewer system to the Water Pollution Control Plant (WPCP). There, it is treated before being sent back into the environment. Learn more about this interesting process in our Wastewater Treatment Plant process (PDF).

Stormwater is routed through the City's stormwater sewer system. Visit our Stormwater Management Plan webpage for more information.

View the 2022 Wastewater Treatment Annual Report (PDF)

What can go down the drain?

Optimally, only water goes down your drain!

What goes down the drain affects us all. We as a community are responsible for protecting Lake Superior, our drinking water source.

Thunder Bay's Sewer Use By-law (PDF) defines and limits what you can legally put down our sanitary sewers and storm sewers.

Our PDF brochure, Household Sewer Management, is an easy-to-understand guide to preserving the health of the City's sanitary and storm sewers. 

The Household Hazardous Waste Handout (PDF) is a handy guide to disposing of chemicals, prescription drugs and hazardous waste that you must not put down the drain. Note that pharmacies will take back unused and expired prescription and non-prescription medicines and medical sharps for safe disposal.  

Click for items you should never put down the toilet or drain:

Never use the toilet or drain to get rid of:
  • dental floss
  • rags
  • tampons, applicators or sanitary napkins
  • wipes
  • disposable diapers
  • cosmetics
  • cotton swabs
  • food scraps
  • fat, grease or cooking oils
  • condoms
  • cigarette butts

Your sewer connection

Sewer connections are the joint responsibility of the City of Thunder Bay and the property owner. The City is responsible for the portion of the connection on City property, from the main sewer to the property line, and the property owner is responsible for the connection from the property line to the house, and have a threaded cap.

Your front clean-outfront sewer clean-out and floor drain

According to the Ontario Building Code, sewer and storm connections must have a front clean-out. Front clean-outs are usually located in the basement floor within one metre of the front wall of the house. Your clean-out allows access for inspection and maintenance.

Please ensure your front clean-out is accessible PRIOR to calling with a sewer or flooding problem.

See our info sheet: Your Sewer Connection.

Problem with your sewer connection? Please report it using the contact info at the bottom of this webpage.


Did you know?

The City of Thunder Bay's Water Pollution Control Plant is participating in the Ontario Wastewater Surveillance Initiative. Under this initiative, communities across Ontario collect samples of their wastewater to be tested for evidence of COVID-19 in the population using the wastewater system. This initiative will help determine how wastewater surveillance can be used in conjunction with clinical data as a tool to inform a public health response.

For more about this Provincial initiative, see the backgrounder PDF: Ontario Wastewater Surveillance Initiative.


More information:

2021 Wastewater Cover PhotoWastewater Treatment Annual Report

We prepare a yearly Wastewater Treatment Annual Report (PDF) to meet the requirements of the Ministry of the Environment, Conservation and Parks. The Report contains statistics and a description of the pollution control process. 

Wastewater System Financial Plan

The Wastewater System Financial Plan (PDF) projects the operating and capital plan for 20 years, from 2014 to 2034. Our goal is to achieve financial sustainability, full-cost recovery, and low cost for consumers while keeping the City’s service levels for sewage collection and treatment.

Report a problem

To report online, use the tool below:

Report a Sewer issue 

To report by phone, or for more information, contact Infrastructure & Operations Dispatch 24 hours a day at 807-625-2195.

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