Grease Traps for Christchurch Cafes and Commercial Kitchens

Why grease traps matter

Fat, oil and grease that goes down a kitchen drain cools and solidifies further along the pipe, building up on pipe walls until the line blocks. On a commercial scale this happens far faster than in a home kitchen, and a blocked kitchen line during service is a genuine business problem, not just an inconvenience.

A grease trap intercepts fat and solids before they reach the sewer, giving the kitchen time to have it professionally removed instead of it building up in the pipework.

Sizing a grease trap

Trap size depends on the kitchen's flow rate, which is driven by the number and size of fixtures discharging into it, typical meal volumes, and the type of cooking done. A high-volume fryer-heavy kitchen needs a bigger trap than a small espresso bar doing light food prep.

Undersized traps fill and lose effectiveness quickly, meaning grease starts passing through into the drain regardless of how well it's maintained. We size to the kitchen's actual equipment and volume, not a generic per-seat estimate.

In-ground vs under-sink traps

• Under-sink or under-bench traps suit smaller cafes with lower volumes and limited outdoor space
• In-ground concrete traps suit higher-volume kitchens and are usually installed outside during a fit-out
• In-ground traps need vehicle or pump access for the waste removal contractor
• Retrofitting an in-ground trap into an existing kitchen is more disruptive, so it's worth planning for at fit-out stage even if not needed on day one

Cleaning schedules

Cleaning frequency depends on trap size and kitchen volume, but as a general rule an under-sink trap in an active kitchen needs cleaning every one to four weeks, while a larger in-ground trap might go two to three months between full pump-outs. Waiting until it smells or backs up means it's already been overloaded for a while.

We recommend setting a fixed schedule with a licensed waste contractor rather than reacting to problems, since council trade waste consents often specify a minimum cleaning frequency anyway.

Christchurch City Council trade waste rules

• Commercial kitchens discharging trade waste generally need a trade waste consent from Christchurch City Council
• The consent typically specifies required pre-treatment, including grease trap installation and maintenance
• Records of cleaning and waste removal are often required to be kept and may be requested by the council
• Non-compliant discharge can result in fines and, in repeat cases, disconnection notices

What we do on installation

We assess kitchen layout, equipment and expected volume, size the trap to suit, install it with correct access for cleaning, and connect it in line with the trade waste consent requirements. For fit-outs, we coordinate with the kitchen designer early so the trap location doesn't get boxed in by joinery.

Frequently asked questions