The sink gurgles when the bath empties. The toilet bubbles when the washing machine drains. A gurgling drain is air being pushed or pulled through the water in your traps, and it's usually an early warning of a partial blockage or a venting problem. Catch it now and it's often a small job.
What gurgling usually means
- A partial blockage. Grease, hair, wipes or limescale have narrowed the pipe, so water and air fight to get past.
- A blocked or missing vent. Drains need air to flow smoothly. If the vent pipe on the roof or the air admittance valve (a small plastic valve, often in the loft or boxing) is blocked or stuck, the water pulls air through your traps instead.
- A shared drain backing up. In flats and terraces, a blockage further down can make several homes' drains gurgle.
What you can do
- Clear the plugholes on every sink, bath and shower. See blocked sink or shower drain.
- Flush the pipes with a kettle of hot water and some washing-up liquid down each plughole.
- Check the outside gully where your waste pipes empty outside. Clear leaves, food and silt from the grate.
- Find the air admittance valve, if you have one. If it's stuck shut or cracked, it needs replacing.
When to call a plumber
Call us if several drains gurgle, the toilet bubbles or rises when other things drain, there's a sewage smell, or water backs up anywhere. That points to a blockage in the main waste or drain, which needs clearing before it overflows. See our blocked drains service. A bad smell on its own is covered in drain smells.
Common questions
Why does my sink gurgle when the bath drains?
Usually a partial blockage in the shared waste pipe, or a blocked vent or air admittance valve pulling air through the sink trap.
Is a gurgling drain serious?
On its own, not yet. But if several drains gurgle or the toilet bubbles, a drain blockage is building and should be cleared soon.
What is an air admittance valve?
A small plastic valve on the waste pipe, often in the loft or boxing, that lets air in so drains flow smoothly. It can stick and need replacing.