Grease Trap Requirements in Singapore: PUB and NEA Rules

Food shops and food processing establishments that discharge used water to the public sewer must install a grease trap that intercepts fats, oils and grease (FOG). The rules come from two agencies. PUB governs the design and approval of the trap under the Code of Practice on Sewerage and Sanitary Works (COPSSW), and NEA governs where the trap may sit and who may clean it. This guide sets out what each agency requires, how a trap is sized, and how the approval route runs for a new or renovated food outlet.

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TL;DR

The 2025 COPSSW (3rd edition) requires grease traps for food shops and food processing establishments that discharge to the public sewer.
A trap must be reachable by a licensed general waste collector and must not sit in areas where food is prepared, cooked, stored or served.
Sizing follows the nominal size method of BS-EN1825, and cleaning is recommended at least once every two weeks by an NEA-licensed collector.
The layout is cleared with NEA first, then submitted to PUB with Form F. A qualified person is normally involved in the design.

Who needs a grease trap in Singapore
What goes through the trap and what does not
Where a grease trap must be located
Sizing a grease trap
Cleaning and maintenance
Can an owner install a grease trap personally?
The approval route step by step
Common reasons layouts are sent back
How we approach grease trap design
Support for submissions and drainage design
FAQ
Sources

Who needs a grease trap in Singapore

The COPSSW requires grease traps to intercept excessive FOG from food shops and food processing establishments that discharge to the public sewer (COPSSW, March 2025). In practice this covers restaurants, food courts, hawker-style operations, central kitchens, caterers and food manufacturers.

The reason is operational as much as regulatory. PUB notes that grease can accumulate and encrust the pipe wall, obstruct sewer flow, and cause used water to overflow into premises or public areas (PUB, Grease Trap). A blocked line in a shop unit is a business interruption before it is a compliance matter.

Non-cooking outlets

Not every F&B unit is treated the same way. PUB’s FAQ states that non-cooking outlets such as cafes, confectioneries or snack bars may not need a grease trap, with PUB’s permission, where the used water carries little or no grease (PUB FAQ, updated 9 July 2018). The exemption is not automatic. The operator must show that the discharge profile supports it, and the decision rests with PUB.

A unit that fries, grills, woks or washes greasy cookware should assume a trap is required until PUB confirms otherwise in writing.

Portable grease interceptors

A portable interceptor is not a free substitute for a built trap. Under the 2025 COPSSW, portable grease interceptors may only be used in food shops that have URA approval for a change in land use, where installing standard or non-standard grease traps is not feasible (COPSSW, March 2025). Tenants converting a shop unit to food use should therefore confirm the land use approval first. The licensing side of that process is covered in the approvals that gate a food shop licence.

What goes through the trap and what does not

PUB’s guidance separates the two wastewater streams. Culinary used water from kitchens and food preparation areas must be pre-treated by grease traps, while used water from toilets must bypass the traps and connect directly to the sewer (PUB, Grease Trap).

This has direct consequences for the drainage layout:

Kitchen floor traps, sinks, dishwashing stations and cooking equipment drain to the grease trap.
Toilet and sanitary fittings drain directly to the sewer line, never through the trap.
Mixing the streams overloads the trap with solids and sewage and defeats its purpose.

The separation is decided at the drainage design stage. Retrofitting it after fit-out is slower and more costly than setting the falls and pipe runs correctly from the start. For the wider picture on how site drainage meets PUB rules, see the PUB drainage requirements guide.

Where a grease trap must be located

Location is where many layouts fail. Two conditions apply together:

The trap must sit in an area accessible for cleaning by a licensed general waste collector.
The trap cannot be sited in areas where food is prepared, cooked, stored or served.

Both appear in the 2025 COPSSW. NEA’s circular on the Code of Practice on Environmental Health gives the reason: maintenance of a trap inside a food area creates health and hygiene hazards (NEA circular, effective 1 April 2016).

For a design team, the two conditions pull in opposite directions. The kitchen is where the wastewater originates, yet the trap must be outside the food zone and still reachable by a collector’s vehicle or equipment. Typical solutions involve placing the trap in a service yard, a back-of-house corridor outside the food area, or an external position along the drain run. Each depends on the building’s plumbing stacks, slab levels and access routes, and each should be checked against the NEA clearance before drawings are finalised.

Sizing a grease trap

The 2025 COPSSW requires traps to be sized using the nominal size method in BS-EN1825. The method calculates the maximum flow rate from the connected appliances and applies frequency and impedance factors (COPSSW, March 2025).

Three points help owners understand the result:

Flow follows equipment. The sizing starts from the appliances actually connected, so a menu change or added dishwasher can change the required nominal size.
Standard PUB designs have equivalents. The code treats PUB’s standard circular grease traps, PUB/WRN/STD/040C and 041C, as equivalent to nominal sizes 4 and 2 of BS-EN1825 respectively (COPSSW, March 2025).
Non-standard traps must carry a recognised standard. PUB’s page states that non-standard traps must comply with either BS-EN1825 or ASME A112.14.3 (PUB, Grease Trap).

An undersized trap is the more common failure mode in the field, because the sizing was done for a lighter kitchen than the one eventually operated. PUB suggests that owners consult qualified persons such as registered professional engineers, plumbers or grease trap suppliers when considering additional traps (PUB, Grease Trap).

Effluent limits

The discharge quality limit sits in the Sewerage and Drainage (Trade Effluent) Regulations. A 2024 amendment, effective 1 July 2024, changed regulation 10(1)(e) so that the wording reads “Grease and Oil” and the figure moved from 100 milligrams to 300 milligrams (Trade Effluent (Amendment No. 2) Regulations 2024). Older material that cites 100 mg per litre predates that change, so owners should read the current regulation text and confirm the applicable figure with PUB before specifying a design target.

Cleaning and maintenance

A compliant trap that is never emptied stops working. The COPSSW sets out regular cleaning, ideally at least once every two weeks, by an NEA-licensed general waste collector following the procedures in its Annexes J and K (COPSSW, March 2025). PUB’s own guidance repeats the two-week recommendation and adds that heavier grease loading may call for more frequent cleaning (PUB, Grease Trap).

The collection and disposal of greasy waste is restricted to NEA-licensed general waste collectors under the Environmental Public Health Act (PUB, Grease Trap). Staff should not scoop grease into ordinary bins or flush it elsewhere.

A practical maintenance routine for an operator includes:

Setting a fixed cleaning interval, and shortening it when the kitchen runs at high volume.
Keeping the collector’s service record on site.
Scraping plates and wiping pans before washing so that less grease reaches the drain.
Keeping the trap lid and surrounding area clear so access is never blocked.
Watching for slow drains and odours, which indicate the trap is saturated.

PUB also directs that no culinary used water be discharged, and no running water used, while the interceptor is being maintained. Operators should coordinate cleaning with kitchen downtime.

Can an owner install a grease trap personally?

The regulations do not provide for an owner to install a trap unaided. The route involves professional assessment, PUB and NEA approvals, and typically a qualified person for the design and a licensed contractor for the works (COPSSW, March 2025). Buying a unit and placing it under a sink is not a compliant installation.

The approval route step by step

The sequence matters because a step taken out of order costs weeks.

Confirm land use. The unit must be approved for food use. A change of use goes through URA first.
Prepare the drainage and trap layout. The qualified person sizes the trap, separates culinary and toilet streams, and positions the trap outside food areas yet accessible for cleaning.
Clear the layout with NEA. PUB’s FAQ states that applicants must clear the proposed layout with NEA to confirm environmental health compliance (PUB FAQ).
Submit to PUB. Form F with detailed plans goes to PUB for sanitary works approval, per the same FAQ.
Allow for review time. PUB’s typical response time for notifications of sanitary works by licensed plumbers, including Forms E, F, H and I, is 14 working days (PUB Service Commitment).
Install through a licensed contractor and arrange cleaning with a licensed collector once operating.

Where the unit connects to a new or altered sewer line, the excavation and connection carry their own checks, outlined in the PUB sewer connection steps for qualified persons. Buyers or tenants taking over an existing unit should also review sewerage interpretation plan checks so that existing sewer lines and any trap are understood before committing.

Common reasons layouts are sent back

The trap sits inside or adjoining a food preparation, cooking, storage or service area.
Toilet drainage has been routed through the trap.
The sizing note does not follow the nominal size method or the stated standard.
Access for the collector is blocked by fixtures, shelving or a locked area.
A portable interceptor is proposed without the URA change of use approval the code requires.
The NEA clearance was never obtained before the PUB submission.

Most of these are resolved at the planning stage by a coordinated drainage design rather than by amendment after submission.

How we approach grease trap design

We see grease trap approvals fail less often on the calculation than on coordination. The trap size may be correct, but the position conflicts with the food area rules, or the drain falls do not allow a collector to reach the unit. For that reason we treat the trap as part of the wider drainage and authority submission, not as a product to be selected at the end of fit-out.

Our work for developers, building owners and food operators in Singapore covers the drainage design, the PE endorsement and the statutory submissions in one engagement, so the layout that goes to NEA and PUB is the layout that is later built. Our stated focus is timely, responsive handling of submissions and clear communication on what each agency needs, which matters when a shop opening depends on approval.

Owners who involve a qualified person before the kitchen layout is fixed generally avoid redrawing the plan around a trap that has nowhere to go.

Aman

Support for submissions and drainage design

AEC Technical Advisory Singapore prepares engineering design and authority submissions for construction, architecture and infrastructure projects, including PE endorsement and statutory submissions to agencies such as PUB, URA, BCA, SCDF, JTC, LTA and NEA. For food shop conversions and new kitchens, that means a single team handling the drainage layout, the endorsement and the paperwork.

Project owners can review the scope on the PE endorsement and authority submissions page or browse the full list of services to discuss a unit before the layout is fixed.

FAQ

What are the regulations regarding grease traps in Singapore?

The 2025 COPSSW requires grease traps for food shops and food processing establishments discharging to the public sewer. PUB approves the design, NEA clears the layout from an environmental health standpoint, and cleaning is done by an NEA-licensed general waste collector. Non-cooking outlets may be exempted with PUB’s permission if their discharge has little or no grease.

Where must a grease trap be located?

It must be in an area a licensed general waste collector can reach for cleaning. It cannot be in areas where food is prepared, cooked, stored or served. Both conditions come from the COPSSW and NEA’s environmental health code.

Can an owner install a grease trap personally?

The regulations do not provide for self-installation. The process involves a qualified person’s design, NEA clearance and PUB approval through Form F, and a licensed contractor for the works. An unapproved installation risks rejection and rework.

How is the size of a grease trap calculated?

The 2025 COPSSW requires the nominal size method in BS-EN1825. The designer calculates the maximum flow from the connected appliances and applies the frequency and impedance factors. PUB’s standard circular traps 040C and 041C are treated as equivalent to nominal sizes 4 and 2.

How often must a grease trap be cleaned?

The code and PUB guidance recommend cleaning at least once every two weeks, with shorter intervals for kitchens producing more grease. The work must be done by an NEA-licensed general waste collector.