What to do about a blocked drain

How to tell a slow drain from a real blockage, what is safe to try yourself, and when to stop and call someone.

A slow drain and a blocked one are different problems. A slow drain is usually a build up you can shift; a blockage that has backed up into more than one fitting is often further down the shared run, where a plunger will not reach.

Worth trying yourself

• Clear the trap: the U bend under a sink unscrews into a bucket and is where most kitchen blockages sit.
• A plunger over the plug hole, with the overflow held shut with a wet cloth so the pressure goes down the pipe.
• Hot water and washing up liquid for a greasy kitchen drain, before anything stronger.
• A drain rod or an auger for a gully outside, feeding it in slowly rather than forcing it.

Stop and call someone if

• More than one fitting is backing up at once, or a downstairs toilet gurgles when a sink upstairs drains.
• Waste water is rising up through a shower tray or an outside gully.
• You would need to lift a manhole cover you are not sure about.

Caustic drain chemicals are a last resort, not a first one: they rarely clear a solid blockage, and they make the eventual job more dangerous for whoever has to open the pipe. Tell the plumber if you have used any.

Blocked drain clearance is listed under plumbing on Halo Hive. Every professional is identity checked, background screened and insured, and payment is held until you confirm the job is done.

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Last reviewed 2026-09-28.