Can I unblock a drain myself?

Yes, for minor blockages. Try a plunger first, then a drain snake or a baking soda and vinegar solution. For persistent or deep blockages, or if multiple drains are affected, call a professional — it may indicate a main drain issue.

Who is responsible for blocked drains in a rented property in London?

The landlord is responsible for maintaining drains and pipes in a rental property. However, if the blockage was caused by the tenant (e.g., flushing wet wipes), the tenant may be liable for the repair cost.

What should I never put down a drain?

Never put cooking fat/oil, wet wipes (even 'flushable' ones), coffee grounds, hair, food scraps, or sanitary products down a drain. These are the most common causes of blocked drains in London homes.

Blocked Drain in London? How to Fix It (and When to Call a Plumber)

Q: How much does it cost to unblock a drain in London?

A blocked sink or toilet costs £60–£150 to unblock in London. A more serious external drain blockage requiring jetting can cost £100–£300. Emergency callouts outside business hours add a premium of £50–£100.

A blocked drain is one of the most common household problems in London — and one of the easiest to ignore until it becomes a serious problem. This guide walks you through everything: what causes blocked drains, what you can fix yourself, when you need a professional, and how much it costs in London in 2026.

Signs You Have a Blocked Drain

Water draining slowly in sink, bath, or shower
Gurgling sounds from plughole or toilet
Unpleasant smell from drains
Water backing up or pooling around the drain
Toilet water rising higher than normal when flushed
Multiple fixtures draining slowly at once (sign of a main drain blockage)

What Causes Blocked Drains in London Homes?

The most common culprits in London properties:

Hair and soap scum — the most common cause of blocked shower and bath drains
Cooking fat and grease — solidifies in pipes and gradually builds up over time
Wet wipes — even "flushable" wipes do not break down properly in sewer systems
Food scraps — especially coffee grounds and rice, which clump together
Tree roots — older London properties with Victorian-era drain systems are particularly susceptible
Limescale — London has hard water, which causes limescale build-up inside pipes over time
Foreign objects — toys, cotton pads, and sanitary items flushed accidentally

How to Unblock a Drain Yourself

For minor blockages, try these DIY methods before calling a plumber:

Step 1: Plunger

A standard cup plunger works well for sinks and toilets. Create a tight seal over the drain, push down firmly, then pull up sharply. Repeat 10–15 times. This works for most minor blockages caused by soft debris.

Step 2: Baking Soda and Vinegar

Pour half a cup of baking soda down the drain, followed by half a cup of white vinegar. Leave for 30 minutes, then flush with boiling water. This breaks down greasy, organic blockages.

Step 3: Drain Snake (Drain Auger)

A drain snake — a flexible metal cable you can buy from any hardware shop for £10–£20 — lets you reach blockages further down the pipe. Insert it into the drain and rotate to break up or pull out the blockage.

Step 4: Check and Clear the U-Bend

If the above don't work, place a bucket under the U-bend (the curved pipe section under the sink), unscrew the access cap or the fittings, and clear the blockage manually. Wear rubber gloves.

When to Call a Professional

Call a plumber if:

DIY methods have failed after two or three attempts
Multiple drains are blocked at once (likely a main drain issue)
There's sewage backing up into the property
You notice a persistent bad smell even after clearing the visible blockage
The blockage is in an external drain or manhole
Your property is over 50 years old (tree roots and collapsed pipes are more likely)

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How Much Does It Cost to Unblock a Drain in London?

Type of blockage	Typical London cost
Blocked sink (kitchen or bathroom)	£60–£120
Blocked toilet	£60–£120
Blocked shower or bath drain	£60–£100
External drain unblocking	£100–£200
High-pressure water jetting	£100–£300
CCTV drain survey (to find cause)	£80–£150
Main drain clearing	£150–£400

For a full breakdown of London plumber prices, see our guide: How much does a plumber cost in London?

Preventing Blocked Drains

Use a drain hair catcher in your shower and bath — empty it every few weeks
Never pour cooking fat or oil down the sink — pour into a container and bin it instead
Only flush toilet paper — wet wipes, cotton pads, and sanitary products cause 90% of London's fatbergs
Run boiling water down your kitchen sink weekly to dissolve grease build-up
Get an annual drain check for older London properties — it's cheap prevention against expensive repairs

Frequently Asked Questions

Is Thames Water responsible for blocked drains in London?

Thames Water is responsible for public sewers. The drains within your property boundary — including the pipes leading to the sewer — are your responsibility as a homeowner. If the blockage is in the shared sewer beyond your boundary, Thames Water may deal with it free of charge.

Can chemical drain cleaners damage pipes?

Yes. Commercial chemical drain cleaners can corrode older metal pipes and damage rubber seals. They're only suitable for occasional use in newer PVC pipework. Avoid using them in older London properties or as a regular solution.