HDB Kitchen Plumbing and Gas Rules: Sinks, Pipes, Gas Hobs and Water Heaters
The kitchen is where most of the pipes in an HDB flat meet: water supply, sink waste, sometimes an aircon discharge pipe, and for many homes a gas riser and meter. A kitchen renovation often means moving the sink, hiding pipes behind carpentry or adding a gas water heater, and each of these has HDB rules attached, including who is allowed to do the work.
This guide sums up what HDB's renovation guidelines say about kitchen plumbing and gas works. It is general information, so check the latest rules for your own flat with HDB before you start.
Who must do the work
HDB's guidelines for water and sanitary plumbing works and gas works are clear about licensed personnel:
Water service and sanitary works: you have to engage a Public Utilities Board (PUB) Licensed Plumber. HDB notes that since 1 April 2018, only PUB Licensed Plumbers may carry out these works, although a handyman without a PUB licence can still do simple plumbing works.
Gas service works: you have to engage an Energy Market Authority (EMA) licensed gas service worker.
When you compare quotations, ask who will actually carry out the plumbing and gas items, not just who is doing the carpentry.
Moving the sink
HDB's guidelines cover repositioning a kitchen sink supported by 63mm thick hollow walls with a tiled finish. The conditions are that the thickness of the dapoh slab, including finishes, should not exceed 50mm, and the floor slab must not be tampered with. For repositioning a sink or wash basin in general, the floor slab must not be tampered with.
If the sink waste pipe needs to be diverted to reach the new position, the pipe must not be embedded in the floor slab. It can be embedded within the floor finishes, must comply with PUB requirements, and the work must be carried out by a PUB Licensed Plumber.
Countertops, dapoh and the service yard
HDB's renovation guidelines for building works list these kitchen items as not needing a permit, subject to conditions:
Kitchen counter top and dapoh slab with cement mortar base: a concrete shelf is not allowed, the total thickness of the cement mortar base and tile finishes must not exceed 50mm, and flat owners are responsible for removing and reinstating the fixtures for inspection and maintenance.
Extending the kitchen into the service balcony or yard without removing walls: services within the extended area should not be tampered with, an exhaust fan is not allowed at the service balcony or yard, and only one layer of 63mm hollow block or 80mm glass block can be erected for the sink support.
Ceiling-mounted clothes drying hanger in the kitchen or service yard: fasteners must not exceed 6mm in diameter and 40mm in penetration depth.
If you are thinking of removing the wall between the kitchen and service yard instead, that is a different matter. Our service yard wall guide and HDB renovation permit guide explain what needs approval.
Hiding pipes behind carpentry or boxing
Many owners want exposed pipes boxed up. HDB allows service ducts and piping (excluding gas pipes) to be enclosed using lightweight non-combustible materials, but you need to provide a removable access opening of at least 600mm x 600mm for inspection and maintenance. If a total replacement of the pipes is ever needed, the enclosure will have to be removed at the flat owner's own cost.
A few more points from HDB's plumbing guidelines:
Concealed water or waste pipes: pipes concealed in floor finishes or walls must not tamper with the floor slab or wall, must comply with PUB requirements, and need a PUB Licensed Plumber. HDB discourages this work because it may cause water leakage to the flat below if it is not done properly.
Aircon discharge pipe in the floor: the pipe must be concealed within the floor finishes only, and the floor slab must not be tampered with.
Removing surface-run pipes: this must comply with PUB requirements and be done by a PUB Licensed Plumber. When the surface-run portion of concealed hot and cold water pipes is removed, the pipes must be terminated with compression fitting caps protruding at least 50mm from the wall.
No-drill zones: for flats with concealed water pipes originally provided by HDB, avoid the no-drill zones. HDB provides kitchen and toilet layout plans as a guide.
Fixings: ramsets, nails and screws must not exceed 6mm in diameter and 40mm in penetration depth for all types of flats.
Keep the kitchen weephole clear
Some HDB layouts have enclosed sanitary ducts in the kitchen with a weephole that alerts residents to leaks inside the duct. HDB says these weepholes should not be sealed or blocked with kitchen carpentry or other fixtures, so that a leak can be spotted and repaired early before it damages your renovation. Point it out to your designer before the cabinet drawings are finalised.
Gas pipes, gas meter and gas appliances
If your flat has piped gas, HDB sets these rules:
Gas riser pipe: all gas riser pipes, including the riser branch pipe before the sub-meter, must not be tampered with. If you enclose the riser with lightweight non-combustible materials, you need a fully ventilated removable access, 600mm wide and full height from ceiling to floor, and the enclosure must be removed at your own cost if the piping ever needs total replacement.
Gas pipe alterations: all gas pipe alteration works must be carried out by City Energy Pte Ltd or a Licensed Gas Service Worker (LGSW). Gas pipes must not be embedded in the common partition walls.
Relocating the gas meter: the work must be carried out by City Energy Pte Ltd and comply with the Singapore Civil Defence Force's (SCDF) guidelines.
Removing the gas branch pipe after the sub-meter: a 100mm length of gas pipe protruding from the wall into the kitchen must be kept and capped when not in use.
Gas water heater or gas oven: the installation must comply with City Energy's requirements and be done by an LGSW. Outdoor installation is subject to HDB's approval.
One more rule matters for open-concept layouts. Gas pipe termination and gas appliances are not allowed in sleeping areas or bedrooms, and spaces with gas pipes cannot be converted into bedrooms. Where the flexible space in a 2-room Flexi flat is used as a bedroom and the kitchen has gas, HDB requires a full-height wall with a door between the kitchen and that space. Our 2-room Flexi BTO guide and wet and dry kitchen guide help with planning the layout.
A simple checklist before you renovate the kitchen
Licensed people: a PUB Licensed Plumber for water and sanitary works, and City Energy or an LGSW for gas works
Sink move: keep the dapoh slab within 50mm including finishes, and never hack the floor slab for the waste pipe
Counter and dapoh: no concrete shelves, and keep the cement mortar base plus tiles within 50mm
Boxing up pipes: non-combustible materials with a 600mm x 600mm access opening, and full-height ventilated access for gas risers
Weephole: leave it visible and unblocked
Gas and bedrooms: no gas pipes or appliances in a sleeping area
Layout first: settle the kitchen layout with our HDB kitchen renovation guide before plumbing points are fixed
Test before you pay: run every tap and check under the sink for leaks before your final payment, using our renovation handover checklist
Where Blackwoods Interior stands
Blackwoods Interior Pte. Ltd. (trading as Blackwoods Interior), UEN 201909521M
CaseTrust accredited for Renovation Businesses (the standard tier, not Gold), valid through 28 April 2028
Listed on HDB's Directory of Renovation Contractors (DRC)
Talk to Blackwoods Interior
Planning to move your sink or rework the plumbing in your kitchen? Book a free 30-minute consultation: WhatsApp us at 8754 3212 (Mon-Sat, about 10:00-19:00 SGT) or email Hello@bwi.sg. Visit www.bwi.sg to see more.
Cover image: illustrative concept, not a completed Blackwoods project. This guide is general information based on HDB's renovation guidelines for water and sanitary plumbing works and gas works, and for building works, checked on 1 November 2026. Rules can change, so check the latest requirements for your flat with HDB before you start.
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