Updated September 2026
A grease interceptor does not fail suddenly. It fills, stops separating, and then starts passing grease into the line — and every stage after that is more expensive than the pump-out that would have prevented it.
Stage one: the unit stops separating
An interceptor works by slowing wastewater down so fats and oils float and solids settle. Once the grease cap and solids take up most of the volume, wastewater passes through too quickly to separate. The unit is still there, but it is no longer doing its job.
Stage two: grease moves into your plumbing
Grease that leaves the interceptor cools in the drain line and coats the pipe walls. Capacity shrinks gradually, which is why drains get slower over weeks rather than overnight.
Stage three: drains back up
- Prep and dish sinks drain slowly, then stop draining during peak service.
- Floor drains gurgle, then push wastewater back into the kitchen.
- In a multi-tenant building, the backup can appear in a neighbouring tenant's space rather than yours.
Stage four: the costs stack up
- Lost trading time — a kitchen that cannot drain cannot serve.
- Emergency service at short notice instead of a planned visit.
- Drain line cleaning or jetting on top of the interceptor pump-out.
- Clean-up and sanitation of an area contaminated by wastewater.
- Damage to lids, baffles and tees left under load for too long.
The compliance side
Municipal wastewater rules exist because grease that reaches the public sewer causes blockages and backups beyond your property. Calgary food service establishments operate under the City's Wastewater Bylaw 14M2012 and FOG program, which is built around effective pre-treatment and demonstrable maintenance. A unit that is not being cleaned is difficult to describe as effective pre-treatment, and with no records there is nothing to show. Confirm your own obligations with your municipality.
Odour and staff conditions
Long before a backup, a neglected unit produces sulphurous odour that carries into the kitchen and sometimes into the dining room. It is unpleasant for staff and noticeable to customers, and it is one of the most common reasons operators finally call.
The comparison that matters
A scheduled pump-out is a known, budgeted cost on a date you chose. An emergency call is an unknown cost on the worst possible date, usually with lost revenue attached. The work is the same; the circumstances are not.
This page is general information for commercial operators, not legal advice. Requirements change and enforcement is up to the relevant municipality — confirm the current rules with your city before relying on them.
Frequently asked
How long can a grease trap go without cleaning?
There is no safe universal answer, because it depends on the unit's capacity and how much fats, oils and grease your kitchen produces. The practical limit is the point where the unit stops separating grease effectively, which is why intervals should come from measurements rather than a calendar habit.
Can a neglected grease trap damage the building's plumbing?
Yes. Grease passing beyond the interceptor coats and narrows drain lines, which is why a badly overdue unit often means both a pump-out and line cleaning.