Start by trying this easy fix. Lots of our customers find this works straight away. If not, look below to find out what to do next.

The most important thing is not to worry. Finding a hidden leak in your loo is actually good news, as it means you’re about to start saving water and money – potentially up to £584* a year.

Step 1: Remove cistern lid and check the water
If it’s staying level, the flush unit is probably causing the leak.
This is an easy fix to try yourself – go to step 2.
If it’s high, rising and overflowing into the toilet bowl, the float switch is probably the culprit.
This is a more complicated DIY fix or a job for a plumber. Scroll down to learn more

Step 2: How to fix a flush unit problem
The aim of this fix is to dislodge debris that’s got stuck under the flush unit and is preventing it from fully sealing, causing a continuous dribble down the back of your bowl.

Here’s how to do it:
1. Take off the cistern lid.
2. Find the rubber seal.
3. Lift up the seal with your fingers.
4. Run your finger around to remove limescale and other debris.

…and when to call a plumber

If this level of DIY is potentially a bit tricky or you just don’t have the time, simply call a plumber. Fixing a leaky loo isn’t usually a big job and 70% of leaky loos are fixed on the first visit**. An average repair is around £150†.

• If wiping the flush unit’s rubber seal hasn’t stopped the leak, the seal or the whole flush unit might need to be changed.
• If the water in the cistern is high, rising and overflowing into the bowl, the float switch probably needs to be changed.

You’ll almost certainly need professional help if:

• If your loo is boxed in, and you can’t get to the cistern.
• If the leak is caused by cracked sanitaryware or pipework,

You can find a plumber in the WaterSafe directory, or if you have HomeServe cover, check your policy – you might be able to book a repair. 

Myth: It’s easy to see or hear when a loo starts leaking
Fact: Leaky loos are hard to spot – a monthly check is the easiest way

Leaky loo mythbusters >

*Based on an average dual-flush toilet losing up to 400 litres a day in a metered household, using water costs of £0.003998 per litre. View our latest charges. View Anglian Water's standard charges for sewerage services. **Waterwise, 2020. †£150 is a rounded indicative cost for a straightforward planned leaky loo repair. It is based on local Cambridgeshire plumber labour rates and published UK cost ranges for common toilet repairs. Actual charges vary by fault, parts required, access, VAT and whether a separate call-out fee applies.