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The four-week rule for Toronto grease interceptors
Field Note · November 11, 2026
If you run a commercial kitchen in Toronto, your grease interceptor runs on a schedule set by the City, not by how the drains feel on a busy Friday. The rule is simple once you see it written down, and knowing it well can keep you out of trouble with an inspector.
What the City requires
Toronto's Code of Practice for food service establishments sets the servicing schedule for hydromechanical grease interceptors, the units most people call grease traps. You service the unit at whichever of these comes first:
- every four weeks
- before grease and solids reach 25 per cent of the liquid volume
- before the fats, oils and grease exceed the unit's rated capacity
The full wording is on the City's Grease Interceptor Maintenance page. The City can also approve a different schedule.
"Whichever comes first" is the part people miss. A busy kitchen with a small under-sink unit can hit 25 per cent well before four weeks. In that case, four weeks is the ceiling, not the target.
When eight weeks is allowed
The City may allow up to eight weeks between services if your records show grease and solids stay under 25 per cent of the liquid volume during the first four weeks. That condition is on the same maintenance page.
The key word is records. A longer interval is earned with paperwork, not assumed. If you think your kitchen qualifies, you need a run of service receipts showing measured levels below 25 per cent at the four-week mark.
Other interceptor types have their own rules
- Solids interceptors follow the grease interceptor schedule, and the strainer and vessel are emptied daily.
- Grease recovery devices follow the manufacturer's schedule, with the strainer and vessel emptied daily and a daily maintenance log kept.
- Gravity grease interceptors, the large in-ground tanks, are pumped before grease and solids pass 25 per cent of the liquid volume.
All three are covered on the City's maintenance page. If you are not sure which type you have, check the markings on the unit or the drawings from installation, or ask your service provider at the next visit.
How to measure your own fill rate
You do not need to guess. Ask your service provider to record the estimated grease and solids level on every receipt. The City already says a carrier's receipt should show this, so it is a fair request.
Then track it:
- Write the level from each receipt in a simple log, with the date and the number of days since the last service.
- Note anything unusual about that stretch: a catering order, a menu change, a holiday weekend, a new dishwasher.
- After three or four services, look at the pattern. If levels are always well under 25 per cent at four weeks, you have the start of a case for a longer interval. If they are close to or over 25 per cent, you may need service more often than every four weeks.
A few things push the fill rate up quickly: fryer-heavy menus, sauces and dairy, scraping plates into the sink instead of the bin, and missing sink strainers. The City's Kitchen & Outdoor Practices page covers the habits that keep grease out of the drain in the first place, like strainers on every sink drain and signs reminding staff not to pour grease down it.
Who can do the work
Most kitchens need a professional. The City only lets an establishment service its own interceptor if it produces a low volume of grease and has no stove or fryer. Even then, the kitchen must skim surface grease and solids weekly and fully clean the unit monthly. Everyone else needs a waste carrier approved by the Ontario Ministry of the Environment, Conservation and Parks. Both rules are on the maintenance page.
Why it matters
A full interceptor lets grease pass into the sewer, where it hardens and builds up. The City lists odours, pests such as rats and cockroaches, and drain blockages among the results of poor servicing. If grease from your kitchen blocks or damages a City sewer, the City can charge the cost back to you and take enforcement action under the Sewers By-law, as noted on its Kitchen & Outdoor Practices page.
A simple routine to follow
- Book recurring service at four weeks or sooner, not "when it starts to smell".
- Ask for the grease and solids level on every receipt.
- Keep every receipt on site. The City wants servicing records kept for at least seven years, and our service record checklist shows what each one should include.
- Review your levels every few months and talk to your provider about adjusting the schedule.
When you compare providers, ask each one for a written quote that spells out the service interval, what they measure on each visit and where the waste goes.
Find a company
- Grease trap pumping (4 approved)