Most toilet faults are in the cistern, and most cistern faults are one of three things: a failed flush valve seal, a float valve that is set wrong or worn, or a syphon that has perished. All three are repairable. Leaks at floor level are a different problem and need identifying before anything is replaced.
The running toilet
Water trickling continuously into the pan means the cistern is not holding its contents. There are only two ways that happens: water is escaping from the cistern into the pan, or water is entering the cistern faster than it should and going out over the overflow.
Escaping into the pan
On a modern drop-valve cistern – which is nearly everything with a dual flush button – the flush valve sits in the base of the cistern with a rubber seal. That seal perishes, or picks up grit and limescale, and then it does not seat. You can often confirm it in thirty seconds: put a small amount of food colouring in the cistern, wait fifteen minutes without flushing, and look in the pan. Colour in the pan means the flush valve is passing.
In hard water this is a recurring fault rather than a one-off, because scale builds on the seat that the seal has to close against. Cleaning the seat properly at the same time as fitting a new seal is what makes the repair last.
Overfilling
The float valve – the inlet valve – should shut off cleanly at the fill line. If it is set too high, the cistern fills past the internal overflow and discharges into the pan indefinitely. If the valve diaphragm is worn, it will not shut off fully at all. Both are routine repairs and both present identically.
Weak or incomplete flush
A flush that will not clear the pan is usually not a blockage. In order of likelihood:
- The cistern is not filling to the correct level. Modern cisterns hold a small volume by design and a centimetre low makes a visible difference.
- The dual-flush mechanism is misadjusted so the full flush is delivering the reduced volume.
- The rim channel is scaled up. Water should sweep the whole rim. In hard water the holes block progressively, so the flush stops rinsing and starts dribbling down one side.
- The syphon has perished, on older cisterns with a lever flush. A syphon that has split will not lift the full volume.
- The pan itself is the wrong match for the cistern, which happens after a part-replacement where somebody fitted what was available rather than what suited.
If your flush has weakened gradually over years rather than suddenly, and you live in a hard-water area, look under the rim with a mirror. A rim channel that has closed up is extremely common here and is not fixed by replacing cistern parts.
Leaks, and where they actually come from
Water on the floor around a toilet is worth identifying properly before anything gets replaced, because four completely different faults present the same way:
| Source | Clue |
|---|---|
| Cistern-to-pan seal (close-coupled doughnut washer) | Water appears at the back when flushed, not continuously |
| Inlet connection or isolation valve | Continuous, worst when the cistern is refilling |
| Pan-to-soil connector | Smell as well as water, and it worsens with use. Often a perished or displaced connector |
| Condensation on the cistern | Wet in warm damp weather, no flush correlation, and the whole cistern is beaded. Not a leak at all |
| A leak from elsewhere tracking along the floor | Wet at the toilet because that is the low point, not because that is the source |
The last two matter, because a new toilet will not fix either of them. We would rather spend twenty minutes establishing which it is than fit a pan and have you call back.
Concealed cisterns and wall-hung pans
Concealed cisterns look excellent and they are considerably more work to maintain. Everything that can fail on an exposed cistern can fail on a concealed one, but it is behind a tiled wall. The difference between a manageable repair and a serious one comes down to whether the installer left a proper access panel and whether the frame and valve are from a manufacturer whose spares still exist.
If you are having a bathroom designed, this is worth raising at that point rather than five years later – see bathroom renovations. If you already have one and it is playing up, we will open it up carefully and tell you what we find before doing anything irreversible to your tiling.
Toilet running, leaking or flushing badly? It is almost always a repair rather than a replacement.
Questions we get asked about this
How do I know if my toilet is leaking into the pan?
Food colouring in the cistern, wait fifteen minutes, do not flush, then look in the pan. Colour in the pan means the flush valve seal is passing. It is the simplest diagnostic in plumbing and it takes no tools.
Is a running toilet urgent?
Not dangerous, but on a metered supply it is expensive and it runs twenty-four hours a day. It is also one of the cheapest repairs there is, so there is no good reason to live with it.
Can you repair a concealed cistern without removing tiles?
Usually, provided there is an access panel or the flush plate can be removed to reach the valve – which on most modern frames it can. Where the installer tiled over everything with no access at all, we will tell you the options honestly before anything comes off the wall.
My toilet blocks regularly. Why?
Repeated blockages in the same toilet usually mean something structural rather than what is being flushed – a partly collapsed or poorly falling branch, a build-up in the soil pipe, or a pan that was never properly matched to its connector. It needs looking at rather than plunging monthly.
Should I replace the whole toilet?
Rarely necessary for a fault. Cistern internals are replaceable and pans last decades. Replacement makes sense if you are changing the bathroom, if the pan is cracked, or if the whole suite is an obsolete size that nothing fits.
Are dual flush buttons more likely to leak?
In practice, yes – a drop valve sits in the base of the cistern and relies on a rubber seal against a seat, and that arrangement is more sensitive to grit and scale than the old syphon design, which physically cannot leak through. It is the trade-off for the water saving.
What happens when you call
Call and describe it
You speak to an engineer, not a call centre. Most jobs can be narrowed down on the phone.
We look at it properly
A real diagnosis before a price, and a straight answer if it is not worth doing.
A written quote
Itemised, so you can see what you are paying for.
The job, and the paperwork
Certificates where the work needs them, and what will need attention next.
Where we do this work
Across Norwich and the whole of Norfolk. If you are on the edge of the county, call and ask — we will tell you honestly whether we are the right people.
- Norwich
- Wymondham
- Dereham
- Attleborough
- Aylsham
- North Walsham
- Cromer
- Diss
- Loddon
- Long Stratton
- Watton
- King's Lynn
Need this doing?
Call and describe the problem — you will speak to an engineer, not a call centre. Written quotes, no estimates over the phone.