How much does it cost to unblock a drain?

This is the single most valuable thing on this page, because it can reduce the bill to nothing.

Since 2011, most shared drains and lateral drains — the sections running from your property boundary to the public sewer — transferred to the ownership of water and sewerage companies in England and Wales. If the blockage is in that section, or in a drain shared with neighbouring properties, your water company is generally responsible for clearing it and will normally do so free of charge.

What remains yours is the private drainage inside your boundary serving only your property.

A practical clue: if neighbours are affected too, or if the blockage is beyond your boundary, call your water company before calling anyone else. They will usually attend to establish responsibility, and it costs nothing to ask.

Drainage firms know this. A reputable one will tell you to call the water company first when the symptoms point that way. One that does not is worth being wary of.

Inside the house it is usually fat, grease, hair and soap building up in the waste pipe, or wet wipes in a toilet. Wipes are the single biggest cause of avoidable blockages in the UK, including those labelled flushable, which do not break down like paper does.

Outside, it is more often root ingress, collapsed or displaced pipework, or a build-up over a defect in the pipe.

The distinction matters because it changes what you should pay for. A clear-and-go on a fat blockage is a straightforward job. A drain that blocks repeatedly at the same point is telling you there is a defect, and paying to clear it again every six months is worse value than paying once for a CCTV survey to find out why.

If you have had two blockages in the same place, ask for a survey rather than another clearance.

A CCTV drain survey runs £150–£350 and produces footage plus a report. It is the right next step for recurring blockages, before buying a property with known drainage history, or where a repair is being quoted and you want to see the defect for yourself.

If a repair is needed, ask whether it can be lined rather than dug out. Patch lining and full relining avoid excavation and are usually far cheaper and less disruptive than replacing a run of pipe.

Check your buildings insurance before committing to major work. Many policies cover damage to underground drainage pipes, and some include the cost of tracing the problem. Making the claim first can change what you pay substantially.

And if roots are the cause, cutting them clears the blockage but does not stop them returning — the entry point needs sealing, or they will be back within a couple of seasons.

Call your water company first if neighbours are affected or the problem is beyond your boundary. It may cost you nothing.

Try the simple things on an internal blockage before calling anyone: a plunger, and for a sink, cleaning out the trap under it. Both are within most people's reach and resolve a lot of kitchen and bathroom blockages.

Avoid emergency rates unless water is actually backing up into the property. A slow drain is a next-day job at roughly half the price.

Stop the cause. Fat into a container rather than the sink, drain strainers for hair, and nothing but paper down the toilet — wipes included.

And get a survey rather than a third clearance if the same drain keeps blocking. Repeat clearances on a defective pipe are money spent on the symptom.