The toilet bubbling when the washing machine empties is usually a sign that air is trapped somewhere in the drainage system.
Is this your problem?
The toilet bubbles only when the washing machine drains
What to do
- Run the washing machine and watch the toilet.
- If bubbling starts as the machine pumps water out, the waste pipe is likely struggling to move water and air properly.
- Check any visible waste pipes outside for obvious blockages, leaves, or debris.
- If you have an accessible inspection chamber (manhole), check whether water is backing up when the machine drains.
Safe DIY: Visual checks and clearing obvious debris.
Stop and call a drainage specialist if: Water backs up into the toilet, bath, shower, or inspection chamber.
The toilet bubbles and drains slowly
What to do
- Flush the toilet several times.
- Notice whether the water rises before slowly disappearing.
- Check sinks, baths, and showers nearby for slow draining.
- If multiple fixtures are slow, the main drain may be partially blocked.
A partial blockage often lets water through but prevents air moving freely, causing bubbling.
Safe DIY: Use normal household drain cleaning methods on accessible waste pipes.
Stop and call a professional if: More than one fixture is draining slowly or sewage smells are present.
The toilet bubbles but nothing is blocked indoors
What to do
- Check whether your property has a soil vent pipe, usually a vertical pipe extending above roof level.
- Look from ground level for signs of bird nests, leaves, or damage.
- A blocked vent can prevent air entering the drainage system properly.
When the washing machine discharges a large volume of water, it can pull air through the toilet instead.
Safe DIY: Ground-level visual inspection only.
Stop and call a professional if: The vent pipe needs roof access or specialist equipment.
The toilet bubbles after heavy rain
What to do
- Consider whether the problem appears only during or after periods of heavy rainfall.
- Check external gullies and drains around the property.
- Remove leaves, mud, and surface debris.
Some older UK drainage systems can struggle when excess rainwater enters damaged or overloaded drains.
Safe DIY: Clearing surface debris.
Stop and call a drainage engineer if: The issue returns regularly after rain.
The washing machine drain standpipe overflows as well
What to do
- Stop using the washing machine immediately.
- Check whether the standpipe or waste connection fills with water.
- This usually indicates a restriction further down the waste line.
Continuing to use the machine can cause flooding.
Safe DIY: None beyond basic inspection.
Call a professional: As soon as possible.
The toilet bubbles but everything seems to work normally
What to do
- Monitor the problem for a few days.
- Check whether the bubbling is getting worse.
- Test other fixtures around the house.
- Listen for gurgling sounds from sinks, baths, or showers.
Small bubbles can be an early warning sign of a developing blockage or venting issue.
Safe DIY: Observation and basic checks.
Call a professional if: The bubbling becomes more frequent or other drainage problems appear.
When to call a professional immediately
| Situation | Wait or call? |
|---|---|
| Toilet bubbles occasionally but everything drains normally | Monitor it for a day or two |
| Bubbling is becoming more frequent | Call if it doesn’t improve |
| Toilet or shower backs up | Call immediately |
| Washing machine standpipe overflows | Call immediately |
| Multiple drains are slow or gurgling | Call immediately |
| Sewage smell inside the house | Call immediately |
| Inspection chamber is overflowing | Call immediately |