How to unblock a sink, bath or shower

By DIY Plumbing Guide Editorial Team · Published 20 October 2026

Safe, step-by-step ways to clear blocked sinks, baths and showers, from hot water and plungers to cleaning the trap, plus what not to pour down drains and when to call a professional.

Most blocked sinks, baths and showers are caused by a build-up of hair, soap, grease or food close to the plughole, and can be cleared in minutes without chemicals or a call-out. This guide works from the simplest fixes to the more involved ones. Stop and get help if a blockage keeps coming back or affects several drains.

Before you start

• Remove standing water with a cup into a bucket if you can.
• Wear rubber gloves.
• If you have already poured a chemical drain cleaner down, do not use a plunger or take the trap apart: chemicals can splash. Flush with plenty of water first and follow the product's safety instructions.

Step 1: Clear the plughole

Hair is the usual culprit in baths and showers. Remove the plug or cover (many unscrew or lift out) and pull out any hair and debris. A cheap plastic drain-cleaning strip with barbs can reach further down.

Step 2: Hot water (for grease)

For kitchen sinks blocked with grease, pour a kettle of hot (not boiling, if you have plastic pipes) water down slowly. Repeat a few times. A little washing-up liquid first can help break up grease.

Step 3: Use a plunger

1. Block the overflow hole with a damp cloth, so pressure goes down the drain. On double sinks, block the other plughole too.
2. Run enough water to cover the plunger's cup.
3. Place the plunger over the plughole and pump firmly up and down a dozen times, then pull away sharply.
4. Repeat several times. Use a small cup plunger for sinks and baths, not a toilet plunger.

Step 4: Clean the trap

The trap (the U-shaped or bottle-shaped section under the sink) holds water to stop smells and often collects debris.

1. Put a bucket underneath.
2. Unscrew the trap by hand; most plastic traps have large nuts that turn without tools.
3. Clean it out, check the washers are in place, and refit it hand-tight.
4. Run water and check for leaks.

Bath and shower traps are harder to reach. Some can be cleaned from above through the plughole; otherwise there may be a panel to remove.

Step 5: Use a drain snake

If the blockage is further along, a hand-operated drain snake (auger) can reach it. Feed it in gently, turning the handle to grip or break up the blockage, then pull it out and flush with hot water.

If the blockage is further along, a hand-operated drain snake (auger) can reach it.

About chemical drain cleaners

Chemical cleaners can work on soft blockages but are hazardous to skin and eyes, can damage some pipes and finishes, and may not shift a solid blockage. Follow the label exactly, never mix products, and keep children and pets away. Mechanical methods are usually safer.

Preventing blockages

• Never pour fats, oils or grease down the sink. Let them cool, then put them in the bin. Water companies warn that fat is a major cause of sewer blockages ("fatbergs").
• Use plughole strainers in kitchen sinks, baths and showers.
• Scrape food into the bin or food waste caddy before washing up.
• Flush drains with hot water now and then.

When it's not your blockage?

If several drains are slow, toilets gurgle, or an outside drain or manhole is overflowing, the problem may be in the main drain or the sewer. In England and Wales, water companies are usually responsible for shared sewers and lateral drains outside your property boundary, while you are responsible for drains within it that serve only your home. Contact your water company if you think the problem is a shared sewer.

When to call a professional?

• The blockage keeps returning.
• More than one drain is affected.
• Water backs up into another fitting.
• There is a bad smell or signs of a leak under the floor.

Sources and further reading

• Water UK
• Ofwat (water regulator)
• Water Regs UK: water fittings regulations guidance

Facts checked on 20 October 2026. Spotted an error? Tell us and we will correct it.