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A grease trap is any interceptor, arrestor, tank, or pit situated above or under the ground that allows cooling and separation of grease from used water. Fat, oil, and grease discharged from food establishments are major causes of blockages in the public sewerage system. Without a properly sized and maintained grease trap, grease will enter the sewers and accumulate. This will result in encrustation, which will obstruct the smooth flow of used water in the sewers and cause it to overflow into your premises or other public areas.

All establishments that handle food, including restaurants, coffee shops and hawker centres, require grease traps.

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How does a grease trap function?

Step 1: Coarse solids in used water are removed when the water passes through the screen chamber.

Step 2: Smaller solids in used water are further removed at the strainer bucket.

Step 3: Less dense fat, grease, and oil in used water are separated as the water enters and circulates around the outer ring chamber.

Step 4: Denser remnant solids sink to the bottom of the outer ring.

Step 5: Used water enters the inner ring chamber where it is discharged into the sewer via the outlet pipe through water displacement.

Installation of Grease Traps

When installing a grease trap, you should take note of the following:

a) Grease traps are used to pre-treat only culinary water from the food preparation area and kitchen. Used water discharged from toilets and other sanitary drain lines (private sewers) not serving the food preparation area shall be connected to the sewers and bypass the grease trap.

b) Grease traps are to be installed in a location that is easily accessible for maintenance works. A properly located grease trap can prevent health risks, other public health hazards.

c) Owners are required to seek NEA's and PUB's approval before installation of grease traps.

For more information on installing your grease trap, you can refer to PUB's Code of Practice on Sewerage and Sanitary Works here.

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Maintenance of Grease Traps

Maintaining your grease trap properly can help prevent:

a) Offensive odours

b) Flow blockage due to accumulation of oil and grease in the sewerage system

c) Overflow of used water from blocked sewers onto your premise or other public areas

Besides giving your patrons a pleasant eating environment, the measures that you put in place will also help to protect our precious water resources and address public health concerns.

Food establishments may refer to the following recommended frequencies for maintenance. The interval to carry out maintenance work is dependent on many factors such as the condition of your private sewerage system, and you may need to increase the maintenance frequencies accordingly to site-specific conditions

Download this guide to learn more about how you can maintain your grease traps.

S/N Maintenance Activity for Food Establishments (Hawker Centres, Eateries, Coffeeshops, including those in Malls) Carried Out By Recommended Frequency
1 Cleaning maintenance of grease traps Licensed General Waste Collector At least once every 2 weeks (to increase if culinary water contains a higher Fats, Oil, and Grease loading.)
2 Cleaning/flushing of private sewerage system to eliminate any blockage or accumulation of encrusted grease.
Sanitary contractor At least once every 6 months
3 CCTV inspection of private sewerage system for any leakage, encrusted grease, or damages.
PUB-registered CCTV contractor
At least once every 5 years
4 Visual inspection of inspection chambers, grease traps, and other appurtenances 
Licensed plumber
At least once every 5 years