Why does my toilet keep running after flushing?
Common causes of a constantly running toilet, what to observe and when a plumber is needed.
Updated 9 September 2026 · 4 min read
The common causes
Water continuing to enter the pan is commonly caused by a worn flush seal, a sticking fill valve, an incorrectly set float or debris inside the cistern mechanism. Concealed cisterns can take longer to access and may need model-specific parts.
What to tell the plumber
Say whether the water runs constantly or stops after several minutes, whether moving the flush button changes it and whether the cistern is exposed or concealed. A photograph inside an accessible cistern and one of the flush plate can help identify the mechanism.
Do not ignore continuous flow
A running toilet can waste a substantial amount of metered water and a failing valve can worsen. If the cistern begins overflowing outside the pan, isolate its water supply if safe and arrange prompt repair.
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