Grease Trap Sizing and Capacity Basics

Sizing is the quiet reason some kitchens can never get on a comfortable interval. If the unit is too small for the kitchen it serves, no schedule feels reasonable — it is always nearly full.

How capacity gets described

• Small in-kitchen traps are often rated by flow rate and grease retention capacity rather than total volume.
• In-ground interceptors are usually described by total volume, in gallons or litres.
• Both numbers matter: flow rate decides whether separation can happen at all, and volume decides how long it lasts between services.

What drives the size you need

• Which fixtures and equipment drain into the unit.
• How much fats, oils and grease your menu and cooking methods produce.
• Peak flow, not average flow — the busiest half hour is what has to separate properly.
• Operating hours and days per week.
• In shared buildings, every tenant contributing to the same unit.

Signs a unit is undersized

• It reaches capacity well before any reasonable interval has passed.
• Grease appears at the outlet side shortly after a service.
• Cleaning it more often is the only thing keeping drains clear.
• Kitchen equipment or hours were added after the unit was installed.

Shorter intervals versus a bigger unit

A shorter interval is a legitimate answer when a unit is close to right. When it is genuinely undersized, more frequent servicing is only a way of paying for the wrong equipment forever, and replacement or upsizing is worth pricing out. That is a plumbing and permitting question, so it goes through your plumber and municipality — what we can give you is measured evidence of how fast the unit actually loads.

How to find out what you have

• Look for a manufacturer plate or stamp on the unit or its lid.
• Check building drawings or the mechanical schedule if you have them.
• Ask your landlord or property manager in a leased space.
• Have it measured and recorded on a service visit — depth, dimensions and condition.

Why we measure every visit

Depth, grease-cap thickness and solids readings taken over a few visits turn sizing from an argument into arithmetic. If the numbers show the unit fills faster than its capacity should allow for your volume, that is a sizing conversation with real evidence behind it.