What to check first
Lift or unscrew the strainer over the drain before you do anything else. It catches grease, food scraps, soap scum and hair before they reach the trap, and it is the fastest thing to check and clear by hand or with a gloved finger. Do not push anything further down into the pipe.
If the strainer is clear, try a sink plunger sized to seal over the drain opening, with no chemical drain cleaner already in the pipe. Note whether it moved any water at all, and whether the choke is confined to this one sink or affects another fixture too — that single fact decides whether this is yours to finish or a plumber's job.
Do not pour a second bottle of chemical drain cleaner onto standing water, and do not open the trap under the sink if you are not confident putting it back together without a leak.
The likely causes, in order
Grease, food, soap scum or hair at the strainer (most common). The strainer over the drain opening is the first place to check. It catches grease, food scraps, soap scum and hair before they reach the trap, and in most homes this is where a sink choke starts and where it is easiest to clear by hand.
A blockage in the trap or the first length of waste pipe. If the strainer is clear but the sink still drains slowly, the blockage is usually in the trap just underneath, or the first length of waste pipe behind it. PUB's simple-works list covers clearing and flushing a discharge pipe, drain-line or fitting, so this is still yours to try before calling a plumber.
The branch pipe or shared line, past your own sink. If more than one fixture backs up, or a plunger at the sink has no effect at all, the blockage is likely past your own pipework. HDB states you need to maintain the sanitary branch pipes in your flat, while the Town Council is responsible for the main sanitary pipes. A blockage confined to one sink is yours to fix; one that spreads to other fixtures or affects a neighbour points to the shared line.
When to call, and who
Stop and call a plumber if water backs up through more than one fixture, the water rises rather than drains slowly, or the smell suggests sewage. Do not add chemical drain cleaner on top of standing water before trying a plunger, because the combination risks a splash-back.
If the blockage affects a neighbour too, or you suspect the main sanitary pipe is involved, contact your Town Council before booking a private plumber — that section is not yours to open.
What it costs
Ask what the quote covers: the call-out fee, whether it is waived if you proceed, and whether opening the trap or a longer waste run costs more than a straightforward strainer clear.
Tell the plumber what you have already checked — the strainer, whether a plunger did anything, and whether other fixtures are affected — so the quote matches the job you actually have.
Who to call, and how to judge them
A plumber checks the strainer and trap first, then works along the accessible waste pipe, and only traces the blockage back toward the branch or shared line once the section under the sink is confirmed clear. All regulated water service and sanitary plumbing works must be carried out by Licensed Plumbers, except for simple plumbing works that can be carried out by handymen — and PUB names clearing a blockage in a sink, floor trap, water closet or sanitary appliance as one of those simple works.
An ACRA registration confirms the business exists, nothing more. Once the job needs opening concealed pipework rather than the trap under the sink, ask specifically whether the person doing the work holds a PUB Licensed Plumber licence.
Frequently asked questions
What usually causes a sink to choke in a Singapore home?
The strainer over the drain opening is the first place to check. It catches grease, food scraps, soap scum and hair before they reach the trap, and in most homes this is where a sink choke starts and where it is easiest to clear by hand.
Can I clear a sink choke myself, or do I need a licensed plumber?
All regulated water service and sanitary plumbing works must be carried out by Licensed Plumbers, except for simple plumbing works that can be carried out by handymen — and PUB names clearing a blockage in a sink, floor trap, water closet or sanitary appliance as one of those simple works.
Sources
- PUB, "Plumbing Works" (fetched 15 Sep 2026)
- PUB, "Licensed Plumbers" (fetched 15 Sep 2026)
- HDB, "Pipes" home care guide (fetched 15 Sep 2026)
Compare plumbers providers and give each the same facts: whether the strainer was clean, what a plunger did, and how many fixtures are affected.
