LargeCommercial Grease Traps

Sizing depends on peak flow rate, the number of appliances discharging to the trap (sinks, dishwashers, floor drains) and daily covers served in a catering operation. Undersizing leads to poor separation and frequent overflows, so it's worth calculating flow rate in litres per second rather than just guessing on volume. If you're unsure, get in touch with our team with your kitchen layout and we'll help you match the correct model.

GRP (fibreglass) grease traps are corrosion-resistant, lightweight and well suited to below-ground or outdoor installation where they won't be affected by rust. Stainless steel units are typically used indoors, close to the kitchen, where easy access for daily maintenance is a priority. The right choice usually comes down to installation location and how the trap will be cleaned and emptied.

Not necessarily — smaller stainless steel traps are often installed above ground indoors, close to the point of discharge, for ease of cleaning. Larger capacity GRP or concrete units serving industrial facilities are more commonly installed below ground outside the building, particularly where space indoors is limited. Below-ground installation requires proper access covers at grade for emptying and inspection.

This depends entirely on trap size and volume of fatty waste produced, but most commercial kitchens need emptying weekly to monthly, while larger industrial traps may go longer between services. Regular emptying by a licensed waste carrier is a legal requirement, and leaving it too long risks grease carrying over into the sewer and potential fines. Keep a maintenance log, as your local water authority or environmental health officer may ask to see it.

Commercial kitchens and food processing facilities are generally required under trade effluent consent conditions to prevent fats, oils and grease (FOG) from entering the public sewer. Your local water company sets the specific discharge limits and may require a trade effluent permit alongside the grease trap itself. Waste collected from the trap must be disposed of by a licensed waste carrier with proper documentation, so keep transfer notes on file.

Standard kitchen grease traps are designed specifically for fats, oils and grease from food preparation, and aren't suitable for mineral oils or industrial process water — for that you'd need a dedicated oil interceptor. Mixing waste streams can overload the trap and cause non-compliance with your trade effluent consent. If your site produces both types of waste, they should be routed to separate, appropriately specified units.