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Frequently asked questions about grease traps

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A grease trap (or interceptor) is a plumbing device that collects grease and prevents it from going down your drain. This device must be installed by a licensed plumber.

The City of Winnipeg Sewer By-law requires that all commercial, institutional, and food service preparation operations have a grease trap.

A grease trap protects your sewer and saves you money. Fat, oil and grease hardens as it cools and sticks to the inner lining of sewer pipes, eventually causing a blockage. By preventing grease from going down your drain, you won't have to spend money:

  • cleaning and disinfecting after sewer backup,
  • hiring a contractor to clean the buildup from your sewer,
  • repairing or replacing your sewer pipe if the blockage is severe.
  • Grease trap and sink photo and grease trap close up photoWastewater enters the grease trap from your sinks and dishwashers.
  • The water cools and the grease and oil harden and float to the top of the trap.
  • The rest of the wastewater flows through the trap and out the exit pipe to the sewer.
  • The grease, oil and fat remain in the trap.

The both do the same thing – collect grease and prevent it from going through your private sewer service pipe into the City sewer. They differ only in size and location. Grease traps are fitted to the plumbing inside a facility, usually under the sink, and grease interceptors are outside the facility a few feet under the ground and are very large.

A licensed plumber can determine which of these devices is best suited for your facility. They will consider the volume and flow rate of wastewater from your sinks, dishwashers and mop sinks to determine proper sizing.

Blockages will occur if the trap is not cleaned often enough. A grease trap which is not cleaned will eventually clog.

Yes. The ground up solids from food waste grinders (or garburators) settle to the bottom of the trap and take up room. The trap will clog up with grease more quickly and will need to be cleaned more frequently.

Grease traps back up either because they need to be cleaned or because an outlet is blocked. If you buy a large unit you will need to clean it less often because it will hold more grease. But all grease traps will clog if you don't remove grease regularly.

All grease traps will clog if you don't remove grease regularly

Clean under-the-sink grease traps weekly. If grease traps are more than 50% full when cleaned weekly, then clean them more frequently.

Yes. A grease trap not only collects grease, it removes fats and oils, such as:

  • fats from butter, margarine, shortening and mayonnaise,
  • cooking oil,
  • salad oil,
  • grease from cooking or baking.
  • Use dry paper towels or a spatula to wipe all grease and food waste from cookware into the garbage before washing in the sink or dishwasher.
  • Use strainers in your sinks to catch food waste. Empty the strainer into the garbage.
  • Put greasy foods in the garbage, not down the drain or in the food waste grinder.
  • Pour small amounts of cooking oil and grease into a container with a tightly sealed lid (e.g., coffee can, small ice cream pail) and once it hardens, put it out for regular garbage collection. Do not pour it down the drain.

Yes. The maintenance log is a record of how often you clean the trap and how full it is each time. It is required under the Sewer By-law to ensure that maintenance is performed regularly. The by-law also requires that the maintenance records for the previous 12 months be available for inspection.

Yes. Some businesses collect and reuse large amounts of cooking oil.

Yes. Under part 13, section 80, of the Sewer By-law, an owner could pay penalties of:

  • for a first offence, a fine of not less than $1000.00
  • for a second offence, a fine of not less than $2500.00
  • for a third offence, a fine of not less than $5000.00

In addition, the City can take remedial action at the owner's expense. As a result, the owner could be charged the following:

  • the cost of sewer cleaning to clear grease blockages,
  • the cost of correcting problems in neighbouring properties (e.g., sewer backup) as a result of violating the By-law requirement to have a properly functioning grease trap.

You can request a conditional waiver if there is no cooking or cleanup on site. We will review your operation to determine if a waiver is appropriate.

Contact 311

Last updated: June 29, 2018

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As the property owner, you own the sewer pipe from your building to the City's sewer main. This includes the part under your property and the part under City property

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