What are Grease Traps?

Grease traps have been used since Victorian days. They are used to reduce the amount of fats, oils and greases (FOG’s) that enter the main sewers. Effectively they are boxes within the drain run that flows between the sinks in a kitchen to the foul sewer system. They only have waste water flowing through them and are not served by any other drainage system such as toilets.

They can be made from a number of different materials; e.g. Stainless Steel, Mild Steel, Plastics, Concrete, Cast Iron. And range from 40 litres capacity to 45000 litres and above capacity.
They can be located above ground, below ground, inside the kitchen or outside the building.

How do they work?

They work on the basic principal that FOG’s float on water and solid particles sink. The inflow of waste water from the sinks is slowed by baffles causing the separation of oils, water and food particles within the unit. A trap on the outlet prevents FOG’s from flowing directly through the unit. Thus these FOG’s are retained within the unit along with food particles and clean water flows through it. The retained waste collected within the unit needs to be removed at regular servicing intervals.

How effective are they?

The effectiveness of a grease trap depends largely on where it is sited, it’s size and design. On average a single stage grease trap will retain between 50% and 90% of the FOG’s that enter it. A single stage unit has a single chamber for trapping FOG’s. To increase the efficiency of a grease trap it can be divided into 2 or 3 chambers so that each chamber separates between 50% and 90% of the FOG’s that enter it.

Where are they needed?

Revised Building Regulation requires all new builds and refurbishments of hot food premises to have an effective means of grease removal on site. They are required on all sites that prepare hot food for the public or staff. Sites include the following:

·         Hotels
·         Restaurants
·         Cafes
·         Conference Centres
·         Food Manufacturers
·         Golf Courses
·         Sports Venues
·         Theatres
·         Schools and Colleges
·         Pubs and Inns
·         Take Aways
·         Bakeries
·         Canteens at factories and offices