If you're sizing a grease trap for a Toronto or GTA restaurant, the two questions that matter on day one are: do you need an under-counter trap or an in-ground tank, and what's that going to cost. For most projects, internal under-counter traps install from around $2,000; in-ground grease tanks typically run $25,000–60,000 once you include cutting and re-pouring concrete, excavation, and the tank itself. We size this with the engineer at the proposal stage so it doesn't blow up your budget mid-construction.
The decision is driven by how much greasy water your kitchen produces and where the city's plumbing reviewer will let you put the equipment. A small QSR with one prep sink and a single fryer can almost always run an internal under-counter trap. A full-service kitchen with a three-compartment sink, dishwasher, pot wash, and a couple of floor drains in the cooking zone usually needs an in-ground grease tank outside the building or in the basement.
Quick rule of thumb we use on a site walk: if your connected fixtures push more than about 75 gallons-per-minute of drain flow, plan for an in-ground tank. Below that, an internal trap is usually accepted, and you save the excavation cost.
We coordinate the trap selection with the mechanical engineer and the city's plumbing reviewer before drawings get stamped. That's the cheapest moment to catch a problem — the trade coordination work we do at this stage is what keeps the trap from becoming a mid-construction surprise.
Drain flow capacity is measured in gallons per minute — how much greasy water moves through the trap at peak. The bigger your kitchen, the higher the gallons-per-minute rating you need. The provincial plumbing code has a sizing method based on drainage units (sometimes called fixture flow), which the engineer multiplies by a factor to land on the right size.
Here's what we typically spec:
Hand sinks and mop sinks generally don't get connected to the trap. The cooking-side floor drains, the three-compartment sink, the pot wash, the wok station drain, and the dishwasher discharge are what drive the size.
The price gap between an internal trap and an in-ground tank is the single biggest budget swing on the plumbing side of a restaurant build-out, so it's worth getting the right answer before you sign the lease.
If your concept is a casual full-service or hotpot kitchen and the landlord won't accept an internal trap, the tank cost lands inside your overall build-out budget — see our restaurant build-out cost guide for Toronto in 2026 for how that fits into the bigger number. For hotpot specifically, where drain volume is unusually high, we cover the kitchen-mechanical realities in the hotpot construction breakdown.
When the plumbing inspector walks the site at rough-in and again at final, they're looking at four things on the trap:
The city's plumbing rules in Toronto and Peel cap how much grease can leave your building in the wastewater, and the inspector is the person who enforces that. Mississauga and Brampton operate under Peel's grease and sewer rules; Vaughan, Markham, and Richmond Hill each have their own version. The size of trap that satisfies one city's reviewer will usually satisfy the others, but the install details (location, venting, cleanout access) sometimes vary.
Cleaning frequency and hauler manifests are operational realities, not paperwork you can skip. The public health inspector and the city's plumbing rules both expect to see records.
A trap that gets skipped on cleaning emulsifies — hot dishwasher water mixes the grease back into the water and it leaves the trap, which both fails the city's discharge limits and clogs your plumbing downstream.
These are the things our pre-construction team flags before the trap goes into the drawings, not after:
For more on how trades line up at this stage, our project experience page shows the kind of restaurant work we coordinate end-to-end.
For the broader permit and approval picture in Ontario, our restaurant permits guide for 2026 walks through who reviews what.
Q: Can I put an in-ground grease tank in the basement of a Toronto restaurant?
A: Sometimes — it depends on slab capacity, ceiling height, and access for the pump truck hose. The city's plumbing reviewer will check that it's vented and accessible. We get the structural engineer to confirm slab work before quoting.
Q: Do I need a grease trap for a bubble tea or coffee shop?
A: Usually a small internal trap, yes. Even no-cook concepts produce some grease from milk, syrups, and rinse water, and the city's plumbing rules apply broadly. The trap is small (around 20 gallons-per-minute) and cheap.
Q: How big a trap does a hotpot restaurant need?
A: Hotpot drives heavy drain volume and grease load — most hotpot kitchens need an in-ground tank in the 500–1,000 gallon range. We size with the engineer based on station count and broth volume; see our hotpot construction breakdown for the wider mechanical picture.
Q: How often does the trap actually need to be cleaned?
A: Internal traps every week by staff. In-ground tanks every 60–90 days by a licensed hauler. Skipping cleanings is the most common reason a kitchen fails the city's grease discharge limits.
Q: What happens if my trap is undersized?
A: Backups within months of opening, gurgling drains, and grease leaving the building above the city's allowed limit. Fines can be significant, and the fix is replacing the trap — which is far more expensive than sizing it right at the proposal stage.
Q: Are bacterial additives allowed to reduce cleaning frequency?
A: No — the city's grease and sewer rules prohibit additives that delay grease separation, because they let grease pass through into the sewer. Mechanical separation is the only accepted method.
Q: Does the kitchen exhaust system affect grease trap sizing?
A: Not directly — the hood handles airborne grease, the trap handles waterborne grease. But a heavy-cooking kitchen typically has both, and we coordinate them together. Our commercial kitchen ventilation guide covers the hood side.
Q: Who's responsible for the grease trap — landlord or tenant?
A: Usually the tenant installs and maintains it as part of the fit-out, but base-building plumbing capacity is the landlord's. If the landlord didn't bring sufficient drain capacity to the suite, that's a base-building deficiency worth pushing on in the work letter. See our FAQ page for more on lease and TI patterns.
We do the trap math with the engineer before you sign the construction contract, so the cost is locked in and the inspector signs off on first try. If you're planning a restaurant in Toronto, Mississauga, Vaughan, Markham, Richmond Hill, Brampton, or Oakville, request a kitchen plumbing review or call 647-477-7999 — we'll walk the space, run the sizing, and give you a real number.
For the bigger picture on restaurant construction across the GTA, see our restaurant construction overview.