Plumbing

How to fix a slow-draining sink without calling a plumber

5 min readReviewed 18 Jun 2026

A sink that drains slowly — rather than not at all — almost always means the passage is narrowed by build-up, not fully blocked. In most cases you can clear it yourself in about 15 minutes with tools you already own. Here's the order to try things, and the point where it's worth calling a professional.

What's actually causing it

In most Singapore homes a slow drain is grease, food debris, hair or soap scum building up in the U-bend — the curved pipe directly under the sink. Because water still passes, the fix is usually to clear that build-up rather than to break through a solid blockage.

Before you start

Clear everything out from under the sink and lay down an old towel. You'll be working with dirty water, so keep a bucket and a rag within reach.

Try these, in order

Clear the strainer and stopper. Remove the drain strainer or pop-up stopper and pull out any visible gunk. This alone fixes a surprising number of slow drains.
Flush with boiling water. Pour a kettle of just-boiled water down in two or three stages, a few seconds apart, to soften grease. (Go gently if your pipes are old plastic — see the warning below.)
Baking soda and vinegar. Pour in about half a cup of baking soda, then half a cup of white vinegar. Cover the drain for 10–15 minutes, then flush with hot water.
Plunge it. Fill the sink with about 5cm of water, seal any overflow hole with a wet cloth, and plunge firmly 10–15 times. The water helps the plunger build suction.
Clean the U-bend (trap). Put a bucket underneath, unscrew the two collars on the U-bend, and clear out the trapped debris. For a kitchen sink this is the single most effective fix.

What to avoid

Chemical drain cleaners as a first resort. They're harsh on older pipes and seals, dangerous if they splash, and useless against a solid blockage — the caustic liquid just pools on top of it.
Over-tightening plastic collars when you reassemble the trap. Hand-tight plus a quarter turn is enough; forcing them cracks the plastic and causes a leak.

When to call a professional

If the water is fully blocked, backing up into another fixture, or you smell sewage, the blockage is likely deeper than the trap. And if the pipes under the sink are corroded or already weeping, stop — a botched repair can flood the cabinet. That's the point to get a handyman or plumber with a drain snake.

The short version

Nine times out of ten, clearing the strainer and cleaning the U-bend fixes a slow sink. If you've done both and it's still slow, the clog is further down the line — worth a professional's time rather than more DIY.

Rather leave it to a pro?

Post the job on Handyy and get fixed-price quotes from vetted Singapore handymen. Free to post, pay only when it's done.

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