How to Unblock a Sink, Shower or Toilet (and When to Call a Plumber)
Simple ways to clear a blocked sink, shower or toilet, what never to pour down the drain, and when a blockage is a job for a professional.
A slow or blocked drain is one of the most common household problems in the UK, and most can be cleared in minutes without calling anyone out. This guide covers the safe methods for sinks, showers and toilets, what to avoid, and the signs that the problem is further down the pipe.
The quick answer
- Sinks: hot (not boiling) water and washing-up liquid, then a plunger, then clean the trap
- Showers: pull out hair from the drain cover, then plunge
- Toilets: a flanged toilet plunger and patience, never repeated flushing
- Never mix different drain chemicals, and never use them before plunging
- Several drains blocked at once, or a smell from outside, usually means a problem in the main drain
What usually causes the blockage
| Drain | Common cause | Best first fix |
| Kitchen sink | Fat, oil, food scraps | Hot water, plunger, clean the trap |
| Bathroom basin | Hair, soap, toothpaste | Remove pop-up plug, clean, plunge |
| Shower or bath | Hair and soap scum | Clear the drain cover, plunge |
| Toilet | Wipes, too much paper, objects | Toilet plunger |
| Outside gully | Leaves, silt, fat | Clear by hand with gloves, rinse through |
How to unblock a sink
- Remove standing water with a cup or jug
- Pour in a kettle of hot water (not boiling, which can damage plastic pipes and some sinks) with a squeeze of washing-up liquid, and wait a few minutes
- Block the overflow with a damp cloth, then use a sink plunger with firm up-and-down strokes
- If it is still blocked, put a bucket under the U-bend trap, unscrew it by hand, clean it out and refit it, checking the washers sit correctly
- Run the tap for a minute and check for leaks under the sink
How to unblock a shower or bath
Hair is almost always the culprit. Lift or unscrew the drain cover, pull out what you can with gloves or a cheap plastic drain snake, then plunge with the overflow covered. A hair catcher on the drain stops it happening again.
How to unblock a toilet
- Do not keep flushing, as the bowl can overflow
- Put on gloves and lay old towels around the base
- Use a flanged toilet plunger, pushing slowly at first to remove air, then with firm strokes
- Once the water drains, flush once to check
If plunging does not work, a toilet auger can reach further. Never put drain chemicals in a toilet you are about to plunge, as splashes can burn skin and eyes.
What not to do
- Do not mix different drain cleaning products, as some react dangerously
- Do not pour chemicals into standing water and then plunge
- Do not use boiling water on plastic pipes or porcelain
- Do not flush wet wipes, even if the packet says flushable
- Do not pour cooking fat or oil down the sink, even with hot water
When to call a professional
- More than one drain is blocked or slow at the same time
- Water backs up into a bath or shower when you flush the toilet
- There is a bad smell from outside drains or manholes
- The blockage keeps coming back
- You can see water leaking from pipes or the trap
In England and Wales, shared sewers and lateral drains outside your property boundary are usually the responsibility of the local water company. Drains serving only your property are your responsibility. If a neighbour's drains are affected too, contact your water company first.
Frequently asked questions
Does baking soda and vinegar unblock drains?
It can help freshen a slow drain, but it rarely clears a proper blockage. Hot water and a plunger are more effective.
Are chemical drain cleaners safe?
Used exactly as directed, some are, but they can damage pipes and are dangerous if mixed or splashed. Try mechanical methods first.
Why does my sink smell even when it drains?
Usually food or grease in the trap. Remove and clean the U-bend.
How do I stop my kitchen sink blocking?
Scrape plates into the bin, wipe greasy pans with kitchen roll before washing, and use a sink strainer.
Related guides
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