How Fats, Oils, and Grease Affect the Sewer System

Stop the FOG graphic

When fats, oils, and grease are poured down the sink or flushed down the toilet, they can cause big problems for both you and our city. These substances cool and harden inside the pipes, sticking to the walls and gradually building up until they block the flow of wastewater.

This can lead to:

  • Sewage backups in your home and neighbourhood

  • Costly property damage

  • Raw sewage overflows into parks, streets, and waterways, harming the environment

Please think twice before you pour anything down your pipes!

Common Sources of Fats, Oils and Grease

  • Meat drippings and food scraps (e.g., bacon grease, pan drippings)
  • Sauces, gravies, and salad dressings
  • Dairy products like milk, cream, yogurt, and cheese
  • Cooking oils, butter, margarine, lard, and shortening
  • Cosmetics and toiletries such as lotions and some soaps

How You Can Prevent Sewer Blockages

Avoid sewer backups. They are unpleasant, stressful, and costly for everyone! For more information, visit the Region’s website or watch their educational video.

  1. Let FOG cool and harden before disposal.
  2. Scrape it into your green bin.
  3. Alternatively, discard cooled liquids into a container (like a can or bowl).
  4. Use a paper towel to wipe greasy residue and place it in the green bin.

Please note: Liquid cooking oil cannot be placed curbside. For more significant amounts (over 1 litre) from practices like deep frying, store the oil in a sealed container labelled "cooking oil" and take it to a household hazardous waste depot.

Please Note: Depositing anything capable of obstructing the flow of, or interfering with the operation of, a sewer is enforceable through the Region’s Sewer-use By-law. 

clogged pipe

What the City Is Doing

We regularly inspect and clean sewer mains using high-pressure or mechanical devices. In areas with frequent grease buildup, we perform more frequent cleanings to prevent blockages. All sewer mains are inspected once every five years and video-inspected to show the condition of the pipe at the time.

If we find any structural issues during inspections, we schedule immediate repairs to keep the sewer system running smoothly. In freezing temperatures, this incrusted grease is almost impossible to remove, and high-pressure equipment freezes making removal a difficult task. Mechanical methods can be used to dislodge stubborn incrustation, but this can be damaging to the sewer mains.