Why Does My Toilet Keep Running?
A toilet that keeps running after flushing, or that refills intermittently throughout the day and night, is one of the most common plumbing complaints in any home. Beyond being irritating, particularly at night, a running toilet can noticeably increase water usage and, on a water meter, your bill along with it.
The cause is almost always inside the cistern, and while the components involved are fairly simple, they do wear out over time. Understanding what each part does makes it much easier to describe the problem accurately to a plumber, or to recognise when it is worth having someone take a look.
This guide runs through the main causes of a running toilet, how each is typically fixed, and when it is worth calling in professional toilet repairs rather than continuing to jiggle the handle.
A faulty flush valve or flapper
The flush valve, sometimes called a flapper or siphon depending on the toilet type, sits at the bottom of the cistern and controls the release of water into the bowl during a flush. If it does not seal properly afterwards, water continuously leaks from the cistern into the bowl, prompting the cistern to keep refilling. Over time, the rubber seal on this component can warp, crack, or become coated in mineral deposits, all of which prevent a proper seal.
A misaligned or faulty float
The float, either a ball on an arm or a cup-style float depending on the mechanism, rises with the water level and shuts off the fill valve once the cistern reaches the correct level. If the float is set too high, damaged, or has become waterlogged and no longer floats correctly, the cistern can overfill and run continuously into the overflow pipe, which is often the source of a running sound that never seems to stop.
A worn fill valve
The fill valve controls the flow of water into the cistern and can wear out over years of use, sometimes failing to shut off completely even when the float is in the correct position. This often produces a slow trickling sound rather than a full continuous flow, and is a common cause on older toilets that have never had this part replaced.
Issues with the overflow pipe
If you notice water running from an external overflow pipe outside the property, this usually confirms that the cistern is overfilling due to either a float or fill valve problem, rather than a valve seal issue inside the cistern itself. This is worth acting on promptly, as it wastes a significant amount of water very quickly.
Why it is worth fixing promptly
A continuously running toilet can waste many hundreds of litres of water a day, which adds up quickly on a metered water supply. Beyond the cost, the constant noise is disruptive, particularly for toilets near bedrooms. Most of these repairs are quick and inexpensive compared with the ongoing waste of leaving the problem unresolved.
How the repair typically works
A plumber will usually isolate the water supply to the toilet, remove the cistern lid, and inspect the flush valve, float, and fill valve to identify which component is at fault. In many cases, only one part needs replacing, and the repair can be completed within the standard one-hour minimum charge. Our toilet repair work follows our usual hourly rates of £99 + VAT on weekdays, £120 + VAT in the evening, and £185 + VAT overnight and on Sundays and bank holidays, all excluding VAT.
When replacement makes more sense
If the toilet is particularly old and parts are difficult to source, or if several components are failing at once, it may be more practical to replace the cistern mechanism entirely, or in some cases the whole toilet. A plumber covering Wimbledon and nearby areas can advise honestly on which option offers better long-term value during the visit.
Need a plumber or heating engineer?
We arrange appointments across Wimbledon and south west London at clear hourly rates. Call 020 3727 2578 or request an appointment.