How do I clear a choked sink?

A choked basin and a choked kitchen sink are different jobs. Basins choke on hair, soap and toothpaste, usually in the stopper or the trap just below it. Kitchen sinks choke on grease and food scraps, and grease keeps building up past the trap, out of reach.

In many HDB kitchens the sink pipe does not go into the wall. It drops into a floor trap hidden inside the sink cabinet; that is the hole people find when they empty the cabinet. If that floor trap chokes, the sink backs up even with a clean trap.

Start at the top. The pop-up stopper collects a mat of hair on its underside that you cannot see from above.

1. 1Pull the stopper out. Some lift or twist straight out. Others are held by a rod under the basin: loosen the rod nut behind the waste pipe, pull the rod back, and the stopper lifts free.
2. 2Pull the hair off and scrub the stopper. Run the tap. Many basin chokes end here.
3. 3Still slow? Put a pail under the bottle trap, the round canister under the basin. Unscrew its lower section anticlockwise by hand.
4. 4Tip the contents into the pail. Clear the rest with a thin stick, a wire hook or an old toothbrush.
5. 5Check the rubber washer is seated, screw the section back clockwise, hand tight, and run the tap at full flow. Watch for drips for a minute.

Some basin pipes have a cleaning eye, a small screw cap on the pipe further along. HDB's own home care guide suggests opening it and using the wire hook there when the choke is past the trap.

1. 1Scoop the standing water into a pail until about 5 cm is left. You need some water to plunge, not a full sink.
2. 2Hold a wet cloth firmly over the second bowl or the overflow hole. Otherwise the pressure comes straight back out there.
3. 3Seal a cup plunger over the outlet and push and pull firmly 15 times. Break the seal and watch.
4. 4If it moves, pour a pail of hot tap water with a good squeeze of dishwashing liquid and wait 10 minutes. This softens fresh grease enough to wash through.
5. 5If it does not move, open the trap. A bottle trap unscrews at the base. A U-trap has two large nuts; loosen both by hand over a pail and lift the U out.
6. 6Scrape the grease and scraps out with paper towels and bin them, not down another drain. Refit the trap hand tight and run hot tap water for two minutes.

Grease does not stay where you can reach it. If the trap was clean or only lightly coated and the sink is still slow, the plug is in the pipe beyond, and a plunger will not reach it. That needs a drain spring or a motorised drain machine.

None of them reliably clears a solid choke. What each one actually does:

One piece of advice that ranks on page one is to pour boiling water down the kitchen sink every week. We do not. Hot tap water with dishwashing liquid does the same job on fresh grease, and grease poured down with boiling water only travels further before it cools and sets.

• The sink is still slow after the stopper and trap are clean.
• Water comes up through the kitchen floor trap when the sink drains.
• It chokes again within days of being cleared. The pipe is coated, not clear.
• The trap is cracked, its thread is stripped, or it will not stop dripping after refitting.
• You have used a chemical cleaner and the sink is still full.

In an HDB flat the sink, its trap and the branch pipe to the stack are yours to maintain. The town council maintains the main sanitary pipes, so if neighbours on the same stack have slow drains, call them first. In a condo the stack is the MCST's. Clearing a sink choke or replacing a bottle trap does not need a PUB Licensed Plumber.

A plumber checks the sink, the floor trap and any other fittings on the same pipe, opens and cleans the trap, then clears the waste pipe with a hand drain spring. If old grease runs further along, a motorised drain machine goes through to the floor trap or branch pipe. Most jobs take 30 to 90 minutes.

Some town councils run handyman services for simple jobs in HDB flats; West Coast Town Council's 2024–27 term rate for a choke is $40, office hours, before GST. Check whether yours does.

Or WhatsApp us a photo of the sink and the pipe under it, 24/7. We reply with the likely cause and a price range, and the final price is agreed before work starts. Breakdowns: kitchen sink choke prices and wash basin choke prices.

• Fit a fine strainer in the kitchen sink and empty it into the bin, not the sink.
• Let cooking oil cool, pour it into a container or wipe the pan with paper, and bin it.
• Scrape plates and rice pots into the bin before washing.
• Pull hair off the basin stopper every week or two.
• Open and rinse the bottle trap every few months. It takes five minutes once you have done it once.

A sink that chokes every month or two has a coated pipe. Ask for it to be cleared to full bore with a machine or drain cleaning, not just punched through. A worn trap is a bottle trap replacement, not licensed work.