Grease trap must be installed at an accessible location for workers to clean without giving rise to nuisances, health hazards and hygiene problems during its operation and maintenance.

There are two types of grease traps that are commonly available:
     a)   Standard circular grease traps, which are usually constructed underground; and
     b)   Portable grease interceptors, which are usually installed aboveground.

A portable grease interceptor may be installed only if the provision of a standard grease trap is not feasible due either to space constraint or to other difficulties related to the site. If installed, portable grease interceptors have to be of a size that can meet the loading capacity of the eating establishment. Its design should also allow for the easy removal of the cover for maintenance works.

In addition, a portable grease interceptor must incorporate a mechanical oil-skimming device to automatically remove free-floating grease and oil from the interceptor. You may refer to the Code of Practice on Sewerage and Sanitary Works for more details.

Grease traps shall be sized in accordance with guidelines stipulated in BS-EN1825.

Note:
i. Grease trap capacity shall be based on "nominal size" specified in BS-EN1825
ii. The maximum flow rate for selection of nominal size shall be calculated based on appliances/fittings discharging into the grease trap and typical flow rate and frequency factor in EN 1825-2

Illustrated for reference only-grease trap sizing is to be done in accordance with BS-EN1825

Fat, oil, and grease discharged from eating establishments are some causes of blockages in sewers. Maintaining your grease trap properly can 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.

Practise Source Control
Adopt good practices in the work area to reduce greasy waste discharge from the food preparation area into your grease trap by following these simple tips:
     a)   Cover floor traps at all times
     b)   Pour used oil into a separate container and not into private sewerage system
     c)   Dispose leftover food into rubbish bins
     d)   Use catch basket for the sink.

Establish an Inspection Schedule
Carry out regular visual checks on your private sewerage system and grease trap to ensure that they are in good physical condition and are not damaged in any way that may pose a health risk or safety hazard to the public. The recommended guidelines are as follow:

Daily Checklist
     a)   Check the screen chamber for accumulation of debris that may obstruct the flow of used water into the grease trap.
     b)   Check the strainer bucket for accumulation of debris that may affect the effective capturing of solids in the bucket.
     c)   Collect debris in a disposable bag and dispose of them as solid waste.
     d)   Check that the water in the grease trap is maintained at the required level to facilitate grease separation.
     e)   Check for excessive built-up of greasy waste or if the greasy waste has hardened.
     f)   Check that there is no greasy waste in the inner ring chamber.

You are advised to take immediate steps to repair your grease trap if you notice any damage to your grease trap, or when such damage is brought to your attention by the general waste collector or officers from the relevant authorities - PUB and the National Environment Agency (NEA).

Have A Cleaning/Maintenance Schedule
You should engage only competent person to clean your private sewerage system and grease trap. The interval to carry out maintenance work is dependent on many factors such as loading of your grease trap. As a guide, you may consider to clean your grease trap every fortnight by engaging a licenced general waste collector (Class C).

Cleaning Checklist
     a)   Check that the Contractor is a licensed general waste collector.
     b)   Supervise the Contractor to ensure that the grease trap is cleaned in accordance with the PUB’s recommended steps in cleaning grease traps.
     c)   Check and replace any defective or corroded covers of grease trap.
     d)   Check that the covers of your grease trap are properly covered after cleaning.
     e)   Check that the access to the inspection chambers and covers of your grease trap is kept free from obstruction.
     f)   Check the area surrounding the grease trap is clean and does not pose any threat to public health.

Different food establishments have different oil and grease loadings in their culinary water and hence the frequency they would need to clean their grease traps would vary.

To determine the required cleaning frequency, you would need to do sampling checks on the effluent discharged from your grease trap for its compliance with the Sewerage and Drainage (Trade Effluent) Regulations. These sampling checks must be done by accredited laboratories. As a guide for good preventative maintenance, it is recommended to clean your grease traps at least once every 2 weeks. If you have a higher grease or oil loading in your culinary water, you may need to have more frequent cleaning of your grease trap.

The management of greasy waste including its collection and disposal is governed by the Environmental Public Health Act (EPHA), which is administered by the National Environment Agency (NEA).

The collection and disposal of greasy waste should only be handled by a licensed general waste collector. You may refer to NEA’s website at https://www.nea.gov.sg/ for the list of licensed general waste collectors.

Ensuring your grease trap is cleaned regularly and adequately is your responsibility. The recommended steps for cleaning grease traps are as follows:

You may engage accredited laboratory to carry out regular collection and analysis of water samples from your grease trap. You may refer to the Singapore Accreditation Council (SAC) website at www.sac-accreditation.gov.sg for a list of accredited laboratories located in Singapore. Keep analysis reports for checks by PUB officers.

For samples collected from grease traps, you should test for oil and grease (non-hydrocarbon) concentration in accordance with methods established by the American Public Health Association (i.e. APHA 5520) or equivalent analytical bodies.

The trade effluent sample collected for analysis should be representative of the quality of the used water that is to be discharged into the sewers after undergoing pre-treatment in the grease trap. Sampling may be done at the outlet of the grease trap, which is usually located in the inspection chamber immediately after the grease trap, or from the inner ring chamber of the grease trap.

STEP 1: You need to check that your contractor is carrying out the cleaning task in accordance to PUB’s recommended steps for cleaning grease traps.
STEP 2: If you are already cleaning your grease trap on a fortnightly basis in accordance to PUB’s recommended steps for cleaning grease traps, and are still unable to meet the discharge limits, your grease trap may be inadequate to cater to the volume of used water generated by your eatery.
     a)   Grease traps should be sized in accordance to the amount of culinary water to be treated, and designed to allow for maximum oil-and-water separation efficiency by taking into account factors such as the temperature and velocity of used water entering the grease trap.
     b)   You may consider installing more grease traps in your premises to cope with any increase in the volume of culinary water to be treated. You may consult qualified persons such as registered professional engineers, plumbers, or grease traps’ suppliers to assist you in your consideration.
     c)   You may submit your application online at the PUB website if you wish to install additional grease trap(s) in your premises.

Licensed general waste collectors are responsible for the collection and disposal of greasy waste from your grease trap. They are not responsible for advising you on the maintenance frequency required for your grease trap.

The management of greasy waste including its collection and disposal is governed by the Environmental Public Health Act (EPHA), which is administered by the National Environment Agency (NEA). The Code of Practice for Licensed General Waste Collectors specifies the roles and responsibilities of licensed general waste collectors. It also provides guidelines on good practices in the waste collection business. Licensed general waste collectors are expected to adhere to these guidelines so as to improve the standard of their operations and raise the professionalism of service rendered.

If you have any issues or complaints regarding your licensed waste collector, you may refer the matter to NEA at 1800-2255 632 or email to Contact_NEA@nea.gov.sg.

You may visit NEA’s website at: https://www.nea.gov.sg/

You may visit the following websites for more information:

Alternatively, to speak to PUB on the maintenance of your private sewerage system including Grease Traps, please contact: PUB-ONE (24-hour toll-free hotline): 1800-2255-782