Inflow & Infiltration

Inflow and infiltration


  • The flow of storm water into the sanitary sewer system from sources such as downspouts and illegal sump pump connections through direct or indirect connections


  •  The flow of water into the sanitary sewer system through aged or defective pipes and/or maintenance chambers (i.e. cracks, defective joints, etc.) through soil (both groundwater and rainwater).

Video Demonstration of Inflow & Infiltration:


Smoke Testing in sanitary sewer systems:

  • The purpose of the testing is to make sure the sanitary sewer is working at its best

  • The smoke used in the test has no odour, is safe to your health, and will disappear after a few minutes.

  • The smoke test consists of:
    • Blowing a harmless coloured vapour into the sewer maintenance holes and pipes and observing where the smoke exits from the system
    • The smoke is expected to exit primarily out of maintenance holes on the street and the sewer-plumbing stack at the top of your house
    • It is also possible for smoke to exit storm water catch basins and roof downspouts at the side of a house
    • Smoke is not intended to enter your home, only the internal plumbing system. If it does:
      • The smoke is not harmful to you or your pet’s health
      • It will not damage clothing, draperies or furniture
      • Open a window & leave the room if the smoke is bothering you
  • If you are at home and the smoke enters during testing, note the location of the smoke and contact Manager, Environmental Services at 905-563-2799 ext. 286. If you cannot identify the source of the smoke, please call 9-1-1.
  • Staff from the Town and AMG Environmental will be onsite during the entire process of testing.


Preventing smoke from entering home:

  • Each drain should have a "gooseneck" installed (the floor drain is typically a small, perforated metal plate located near a low spot in the basement floor close to the furnace or laundry room)

  • If smoke enters your home and there is water in the drain, the Town recommends that you contact a plumber.


Goose Neck Diagram

How a "gooseneck" works:

  • The “gooseneck”  section of your drain pipe is the “trap.”

    • The trap allows water to fill that section of the pipe completely.

    • Since vapour and gas cannot travel through water unless under pressure, this effectively “traps” the gas in the sewer portion of the pipe.
    • The vent on your system— the portion of pipe protruding from the roof of the building—prevents the gas from becoming pressurized and allows it to escape outside the structure.
    • These two systems function together to keep potentially harmful sewer gases from entering your structure or home.
    • If there is no water in the trap, the trap is not functioning properly.


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