Why does my toilet keep running?

Water continuing into the bowl usually means either the fill valve is not stopping before the overflow level or the flush valve is not sealing after a flush. Remove only the cistern lid, if it is designed to lift off, and observe which route the water is taking.

If water rises and enters the internal overflow, the float or fill valve needs attention. If the level stays below the overflow but water still passes into the pan, the flush seal may be worn, dirty or obstructed. Concealed cisterns and model-specific mechanisms can be harder to access without damage.

Use the toilet's local isolation valve if it turns freely and fully closes the supply. Do not force a seized valve. A persistent running toilet wastes wholesome water and can hide a component that is close to failing, so arrange a plumber if you cannot identify and isolate it confidently.

Replacement parts must fit the cistern and maintain its intended overflow arrangement. Approved Document G requires suitable sanitary installations and water efficiency; do not block an overflow or defeat a safety route to silence the symptom.

Before buying a part, identify the toilet or valve model and photograph the mechanism. Check whether the cistern is close-coupled, concealed or supplied from stored water. A plumber needs to know whether the sound is continuous, returns every few minutes or starts only after a flush. If water is escaping onto the floor rather than safely into the pan, isolate the toilet if possible and treat it as an active leak rather than waiting for the next convenient maintenance visit.

Sources

• Approved Document G — GOV.UK, accessed 14 November 2026.
• The Building Regulations 2010, Part G — legislation.gov.uk, accessed 14 November 2026.

On Leatmere

See running toilets, fill and flush valves and ball valve.