Blocked Drains, Drain Cleaning and Repairs in the UK
Don’t assume straight away that the main drain is blocked. If it’s only one toilet and the nearest inspection chamber is clear, the problem is probably close to that toilet. If several toilets, sinks or drains are backing up and the chamber is full, the blockage is likely to be farther along the drain. If neighbouring houses are having trouble as well, it may be a shared sewer problem rather than something on your own drain.
What is happening?
Outside drain overflowing
Lift the nearest accessible inspection-chamber cover and look from ground level. If that chamber is full as well, the blockage is farther downstream. If it is clear, the trouble is likely to be between the gully and the chamber.
Work through the likely causesToilet keeps blocking
Flush the toilet while watching the nearest accessible chamber. If the chamber stays clear, keep the investigation close to the toilet. If its level rises, the restriction is farther along the drain.
See what the pattern suggestsSeveral drains affected
A toilet, bath and outside gully backing up together usually share a downstream section. If a neighbour has the same symptoms, check the water company’s responsibility before paying for private work.
Narrow down the locationSame blockage keeps returning
If a drain blocks again at roughly the same point after being cleared, clean it properly and inspect that section. Roots, a stepped joint or a heavy deposit can leave a permanent catch point for paper and solids.
Why blockages recurSuspected broken drain
If a contractor says the drain is badly damaged, ask to see the footage. The useful details are whether the pipe is still round, whether a joint has moved into the flow and whether any part of the opening has actually been lost.
Understand the repair optionsNeed a CCTV survey
If the camera view is mostly dirty water, grease or debris, there is little to assess. Clean the run first so the joints, pipe wall and bottom of the drain can actually be seen.
What a survey can showClearing the blockage is only one part of the job
Rods or high-pressure water will clear many ordinary blockages, but getting the water moving again does not always explain why the drain blocked. If the same section fails again, a camera survey after cleaning may show roots, a stepped joint, a misshapen pipe or deposits that are catching paper and solids.
Equally, a single blockage after inappropriate material has gone down the drain is not evidence that the underground pipe needs lining or excavation.
Responsibility depends on the drainage layout and where in the UK the property is located. If several properties are affected, check with the relevant sewerage provider before assuming the blocked section is yours.
Where to go next
See when high-pressure jetting will remove grease and deposits — and when a damaged pipe still needs repair.
See why roots often grow back when the crack or open joint they entered through is left unchanged.
See when lining is practical and when the damaged section has to be exposed and replaced.