How to unblock a sink with drain cleaner
You will need:
- Chemical drain cleaner
If waste water is slow to drain or simply stays in your sink, there is probably a blockage in the trap or pipework. Most blockages can be fixed with a plunger or chemical cleaner but you may have to remove the trap and clear the blockage. Here's how.
Time to complete job: About 15 minutes
Approximate budget: £10.
For more information, log on to The Association of Plumbing and Heating Contractors.
You can also read companion guides How to unblock a sink, and How to unblock a sink - video
Step 1: First steps
Empty as much water as you can from the sink and pour a chemical drain cleaner down the waste pipe. Leave to react with the blockage.
If the water still does not drain properly, you may be able to force water through with a sink plunger.
Force a rag into the waste pipe to stop water blowing back into the sink. Place the plunger over the plug hole and push up and down quickly to try and force the blockage out of the pipe. Run plenty of hot water to clear the remaining debris.
Step 2: Clearing the trap
If the sink is still blocked, empty out as much water as possible and put the plug in. Place a bowl under the waste pipe and unscrew the U-shaped trap directly under the plug hole. Scrape out any hard fat or food deposits before fixing the trap back in place.
Some very old traps have a nut at the base that can be undone with a wrench for cleaning.
Tip: Always let cooking fat set hard and dispose of in the bin rather than down the sink.