CLEARMASTERS
The short version
What should I do about a blocked drain?
Work out where the blockage is first. If only one sink or toilet is slow, it’s probably close to it, and a plunger or cleaning the trap may fix it. If several are slow, or an outside gully or manhole is overflowing, the blockage is in the main drain: stop using water and call a drainage engineer. Avoid chemical drain cleaners, and if neighbours are affected too, it may be the water company’s sewer.
Interactive
Where’s the blockage?
Tell us what’s affected and the diagram shows where the blockage probably is.
Causes
What causes blocked drains?
Most blockages come from what goes down the drain. Our guide to what not to flush covers the worst offenders.
Wet wipes
Even “flushable” wipes don’t break down like paper. They snag, collect fat and form solid plugs.
Toilets and main drainsFat, oil and grease
Liquid when hot, it sets hard in cold pipes and builds up layer by layer.
Kitchen sinks and gulliesHair and soap
Hair binds with soap scum into thick clogs in traps and short waste pipes.
Baths, showers and basinsTree roots
Roots find tiny cracks and joints, then grow inside the pipe looking for water.
Older clay drainsDamaged or sunken pipes
Cracked, displaced or collapsed pipes catch debris and stop the flow.
Older drains and after ground movementLeaves, silt and debris
Washed into gullies and surface water drains, especially in autumn.
Outside gulliesDIY
What you can safely try yourself
Worth a try
- A plunger on a slow sink, bath or toilet (cover the overflow)
- Unscrewing and cleaning the trap under a sink
- Hot, not boiling, water and washing-up liquid for greasy sinks
- Pulling hair out of bath and shower plugholes
- Clearing leaves from an outside gully, wearing gloves
Best avoided
- Caustic or acid drain cleaners: hazardous, and harmful to septic tanks and treatment plants
- Boiling water down toilets or plastic pipes
- Wire coat hangers: they can scratch, snag and push the blockage further
- Climbing into a manhole or reaching into a chamber
- Hiring a jetter without training: it can damage pipes and cause injury
How we help
How we clear blocked drains
Our engineers carry the kit to find and clear the blockage, and show you what caused it.
For big jobs we bring jet-vac tankers that jet and remove the waste in one go. We don’t subcontract: it’s always our own team and our own vans.
Your drain
A pipe that serves only your property, inside your boundary, is usually yours to look after, including clearing blockages.
Shared drains and sewers
Since 2011, most pipes that serve more than one property, and pipes beyond the boundary, have been the water company’s. If the blockage is there, they should clear it.
Not sure which you have? Our guide to who is responsible for drains has a checker. If you’re on a septic tank or cesspit, the whole system is usually yours.
Prevention
How to stop drains blocking
Only the 3 Ps
Pee, poo and paper. Bin wipes, cotton buds and sanitary products.
Bin the fat
Let fat cool in a pot and bin it. Wipe greasy pans before washing.
Use strainers
Plughole strainers catch hair and food before they reach the pipe.
Planned jetting
For busy kitchens, shared drains and problem runs, regular jetting stops build-up.
Running a commercial kitchen? Read our guide to grease traps and FOG.
Questions answered
Blocked drain FAQs
How do I know where my drain is blocked?
Look at which fixtures are affected. One slow sink or toilet usually means a blockage close to it. Several fixtures, especially downstairs or an overflowing gully, point to the main drain. If you can lift the manhole cover safely, a full manhole means the blockage is further down, and an empty one means it’s between the house and the manhole.
Can I unblock a drain myself?
You can often clear a single sink, bath or toilet with a plunger or by cleaning the trap. Blockages in the underground drain usually need rods or a high-pressure jetter. Don’t climb into a manhole or put your arms into the drain.
Are chemical drain cleaners safe to use?
We don’t recommend them. Caustic drain cleaners rarely clear a proper blockage, can damage some pipes, are hazardous to handle and can kill the bacteria in a septic tank or treatment plant.
Who pays to unblock a drain?
It depends where the blockage is. A drain that serves only your property, within your boundary, is usually your responsibility. Shared drains and public sewers are usually the water company’s. Our guide to who is responsible for drains explains how to tell.
What is high-pressure jetting?
High-pressure water jetting uses a hose and nozzle that blasts water at high pressure to break up and flush out blockages, fat, silt and roots. It cleans the pipe walls rather than just pushing a hole through the blockage.
Why does my drain keep blocking?
Repeat blockages usually mean something in the pipe catches debris: roots, a cracked or displaced joint, a sag, or a heavy build-up of fat or scale. A CCTV drain survey will show what’s causing it.
Is a blocked drain an emergency?
It is if sewage is backing up into the house, a manhole is overflowing or you have no working toilet. Stop using water and call our 24/7 line on 03333 233577.
Can a septic tank cause blocked drains?
Yes. A full septic tank or cesspit, or a failing drainage field, makes drains back up and gurgle. If you’re not on mains drainage, check when the tank was last emptied.
Got a different question? Call 03333 233566 or send us a message.