Toilet Keeps Running: Causes and Simple Fixes

A toilet that keeps running wastes water. Common causes, simple checks and when to call a plumber. Call 020 8050 9933.

Key facts

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A toilet that keeps filling or trickling wastes water and can raise your bill. The cause is usually a worn part inside the cistern, and many are quick to put right.

Lift the cistern lid and look

Check whether water is flowing over the overflow pipe, or trickling from the cistern into the pan. Watch what happens after a flush and see where the water is going.

A leaking flush valve or washer

If water trickles into the pan, the seal that holds water in the cistern may be worn or dirty. Cleaning or replacing the seal often fixes it.

A faulty fill valve or float

If the cistern keeps filling and water runs into the overflow, the float may be set too high or the fill valve may be failing. Adjusting the float or replacing the valve usually solves it.

Hard water and limescale

Limescale can stop valves closing fully. Cleaning the parts carefully can help, though worn parts are best replaced.

When to call a plumber

Cistern parts differ between models, and fitting the wrong part can make things worse. A toilet repair is typically £60 - £100 including VAT, plus the call-out fee. If the toilet is leaking onto the floor, turn off the isolation valve and call us.

Quick tips

Related help

Common questions

How much water does a running toilet waste?

It depends on the leak, but a constantly running cistern can waste a lot over a day. Fixing it quickly is worth it, especially if you are on a water meter.

Can you also fix a blocked toilet?

Yes. See our blocked toilet emergency page. A call-out fee applies, shown before you pay.

Do you replace toilets?

Yes. Toilet replacement is typically £120 - £200 including VAT, plus the call-out fee.

Call 020 8050 9933