What to check first
Lift the floor trap cover before you do anything else. It is the small grated cover set into the bathroom or kitchen floor, and in most flats it is where hair, soap scum and food debris collect first. If it's a kitchen sink rather than a floor drain, check the strainer over the sink outlet the same way — it chokes at the surface for the same reason. Clear anything visible by hand or with a stick, then run water to see if it drains normally.
If the trap itself is clear but water still drains slowly, note which fixtures are affected: one bathroom, the whole flat, or the flat next door too. That single fact tells you whether the fault is yours to fix or the Town Council's, and it is free to establish before you call anyone.
Do not pour a second bottle of chemical drain cleaner onto standing water, and do not push a wire or rod further into the pipe than you can see. Both make a plumber's job harder and slower once one is needed.
The likely causes, in order
Debris at the floor trap grille (most common). The floor trap grille is the first place to check. PUB lists "clearing any blockage in any floor trap, water closet or sanitary appliance" as simple plumbing work anyone may legally do, and it is also where hair and debris collect first in most flats. This is the fastest fix and needs no tools beyond a glove.
A blockage further along the discharge pipe. If the floor trap itself is clear, the blockage is usually further along the pipe behind it. PUB's simple-works list also covers "clearing and flushing any discharge pipe, ventilating pipe, drain-line, fitting... grease trap," work you can still do yourself before calling a plumber. A sink plunger over the floor trap, or a plumber's drain snake through the trap opening, usually reaches this.
The shared branch or main line. If several fixtures back up at once, or a neighbour reports the same problem, the blockage is likely in the shared line. HDB states "you need to maintain the sanitary branch pipes in your flats," while "the Town Council is responsible for the maintenance of the main sanitary pipes." A blockage confined to your own fixtures is your branch pipe; one affecting several households points to the main line.
When to call, and who
Stop and call a licensed plumber if water backs up instead of draining, the blockage returns within days of clearing it, or it reaches concealed pipework — PUB reserves altering or repairing concealed pipes for Licensed Plumbers, not handymen. Sewage smell, water rising rather than falling, or a blockage that returns straight after clearing are all signs the fault sits deeper than the trap.
If the blockage affects your neighbours too, or the main sanitary pipe is involved, contact your Town Council before engaging your own plumber — that pipe is not yours to open.
What it costs
Ask for the call-out fee, whether it is waived if you proceed, and whether clearing an inspection chamber or grease trap costs more than a standard floor trap job before you confirm.
Describe what you have already checked — the floor trap, which fixtures are affected, whether a plunger did anything — so the quote you get matches the job you actually have, not a guess.
Who to call, and how to judge them
A plumber checks the floor trap and the discharge pipe behind it first, then traces the blockage back toward the fixture or, if several fixtures are affected, toward the shared line the Town Council maintains. 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 floor trap, water closet or sanitary appliance blockage as one of those simple works. An ACRA registration confirms the business exists, nothing more. Once the job needs opening concealed pipework, ask specifically whether the person doing the work holds a PUB Licensed Plumber licence.
Frequently asked questions
What is the most likely cause of a blocked drain in my flat?
The floor trap grille is the first place to check. PUB lists "clearing any blockage in any floor trap, water closet or sanitary appliance" as simple plumbing work anyone may legally do, and it is also where hair and debris collect first in most flats.
Can I clear a blocked drain 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 floor trap, water closet or sanitary appliance blockage as one of those simple works.
How much does clearing a blocked drain cost in Singapore?
It depends on where the blockage is and how it is cleared. A floor trap or sink strainer you can reach costs less than a blocked branch pipe. Ask for the total, including any call-out or after-hours charge, before work starts.
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: which fixtures are affected, what a plunger did, and whether the blockage has returned before.
