Slow draining sink or bath
A slow-draining sink or bath is one of the most common plumbing niggles in British homes, and the good news is that it's usually fixable without calling a plumber. The culprit is typically a build-up of hair, soap residue, and other debris collecting just below the plug hole or in the U-bend — a problem that worsens over months of normal use. Whether you're dealing with a sluggish kitchen sink or a bath that takes an age to empty, this guide walks through practical, budget-friendly solutions you can tackle yourself, starting with the simplest methods and progressing to more robust options. Most blockages clear within an hour using household items you'll likely have in your kitchen. However, if water's backing up into other appliances, you smell foul odours, or nothing shifts the blockage after trying these steps, it's time to ring a qualified plumber, as the problem may lie deeper in your drainage system.
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Most likely cause & what to check
Remove and clean the drain cover — hair and soap build-up is the most common cause.
Pour boiling water down the drain in three stages.
Try baking soda and white vinegar: pour half a cup of each, cover, wait 20 minutes, flush with hot water.
Use a plunger firmly 10–15 times.
For persistent blockages, use a flexible drain snake.
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Frequently asked questions
Is it safe to pour boiling water down a plastic pipe?
Yes, generally it's safe, but let the kettle cool for just a minute before pouring so the water is very hot rather than at a rolling boil — this reduces the risk of warping older plastic pipes. If you have older chrome or brass fittings, boiling water poses no risk at all.
Can I use bleach instead of baking soda and vinegar?
You can use a purpose-made drain cleaner or bleach, but the chemical reaction between baking soda and vinegar is gentler on your pipes and just as effective for most household blockages. Never mix bleach with other cleaning products, as this creates dangerous fumes.
How often should I clean my drains to prevent blockages?
A monthly flush with boiling water and the baking soda and vinegar method will help prevent build-up and keep drains flowing freely. Installing a simple hair trap or drain cover in your shower or bath also makes a huge difference.
What's the difference between a plunger and a drain snake, and which should I try first?
A plunger creates suction to dislodge blockages near the surface, whilst a drain snake is a flexible tool that physically breaks up or pulls out debris further down the pipe. Always try the plunger first — it's simpler and often works for shallow blockages, then move to a snake if that doesn't solve it.