DrainUK topic library

Blocked drains

Understand where a blockage may be before paying to clear it.

Choose your drainage question

Read the relevant guide to understand the clues, alternatives and what a contractor should investigate.

A blockage cleared today may return where a pipe has a belly, displaced joint or root ingress.

A WC pan trap can hold an object, while a shared branch can restrict several appliances.

Fats cool and cling to pipe walls, trapping food debris and narrowing the bore.

Hair and soap residue collect around a shower trap before the underground drainage is involved.

Many wipes remain intact much longer than toilet tissue and catch at rough joints or bends.

Roots exploit openings at joints and cracks; they do not need to smash through sound pipe walls first.

Heavy rain can overload a combined system or wash debris into a poorly protected gully.

High-pressure water removes deposits but settings and nozzle selection matter where pipes are fragile.

Start with the symptom you can see, rather than assuming an underground pipe is broken.