Quick answer
Close the angle valve (stopcock), remove the button and lift out the mechanism. If the cistern leaks into the pan, clean or replace the flush valve seal. If it will not fill or will not stop, check the fill valve, its filter and the float height. If the button sticks, adjust its travel or replace it. Test with food colouring before closing it up.
What you need
- Flat and Phillips screwdrivers
- Long-nose pliers
- Small adjustable spanner
- Bucket or bowl and a sponge
- Torch
- Old toothbrush
- Universal flush and fill kit such as Wirquin or Siamp (Leroy Merlin, Bricodepot)
- Original spare part if your cistern is a Roca or Geberit (order it by the model number moulded inside)
- Spare flush valve seal
- White vinegar and a soft scourer
- Food colouring
- PTFE tape
Step by step
- 1
Turn off the water and empty the cistern
Turn the angle valve (the stopcock next to the inlet pipe, on the wall or the floor) a quarter turn. If there is not one, or it will not close, use the main stopcock for the whole property. Flush to empty the cistern and dry the bottom with a sponge.
- 2
Remove the button or the plate
On an exposed Roca cistern, the button usually comes off by turning it or releasing a clip. On a concealed cistern (Geberit, Roca In-Wall, Grohe), the plate comes off with clips or a hidden screw: pull gently from the bottom edge and do not force the frame.
- 3
Take out the flush mechanism
Remove the frame and release the flush bell, which on most models comes out with a quarter turn. If you are unsure, take a photo before touching anything. With the torch, check how the overflow tube and the button rod fit together.
- 4
Clean and check the flush seal
Rub the seal and its seat with vinegar and a soft scourer to remove limescale. If the rubber is hard, misshapen or cracked, replace it. It is the cause of 80% of cisterns that leak into the pan.
- 5
Check the fill valve and its filter
With the water off, unscrew the cap of the inlet valve and clean the filter with the toothbrush. If the diaphragm is stiff or covered in limescale, replace the whole valve. This is what fixes a cistern that will not fill or never stops filling.
- 6
Adjust the float level
The water should sit about 2 cm below the overflow tube, or at the mark moulded into the tank. Use the screw or the thread on the valve to raise or lower the level. A high level is a silent leak into the pan.
- 7
Adjust the button travel
With the button fitted, the mechanism should have 1-2 mm of play before it starts to lift. If the button stays pressed in, loosen the rod or cable a couple of turns. If it does not flush first time, shorten them.
- 8
Refit, turn the water on and test
Put everything back in reverse order. Open the angle valve slowly and let the cistern fill. Flush three times: the small button should release about 3 litres and the large one about 6.
- 9
Do the food colouring test
Put a few drops of food colouring in the cistern and wait 15 minutes without flushing. If the colour shows in the pan, the flush seal is still leaking. Also lay dry tissue paper around the base of the cistern to spot any external drips.
Push-button cistern: symptoms and the part that has failed
A push-button cistern has three systems: the flush (bell and seal), the fill (inlet valve with a float) and the button with its rod or cable. Almost always only one of them has failed, and the symptom tells you which. Before you buy anything, find out which of these cases is yours.
On exposed Roca cisterns (Dama, Victoria, Meridian) everything is visible once you take the lid off. On concealed cisterns, which are now the majority in new-build flats in Valencia, Alicante and Benidorm, you get in through the button opening, which is why it pays to photograph each step.
| Symptom | Likely part | Fix | Part |
|---|---|---|---|
| Constant trickle into the pan | Flush valve seal | Clean with vinegar or replace the seal | €5-15 |
| You hear it refilling every few minutes | Flush seal or high water level | Replace the seal and lower the float | €5-15 |
| Does not fill or fills very slowly | Limescale in the filter or angle valve | Clean the filter, open the valve fully | €0-10 |
| Fills non-stop and overflows | Fill valve or float | Replace the fill valve | €10-25 |
| Button stiff, stuck or does not flush | Rod or cable badly adjusted | Readjust or replace the button | €10-35 |
| Drips on the outside, at the base | Cistern-to-pan seal or flexible hose | Replace the seal or hose | €3-12 |
How to fix a push-button cistern that will not stop filling
This is the fault that wastes the most water: the cistern fills and never shuts off, and the water runs through the overflow into the pan. If the meter keeps turning with everything switched off, this is usually the reason. The cause is in the fill valve: the diaphragm hardens, a grain of limescale sits on the seat or the float is badly set.
First lower the level by a couple of centimetres. If it shuts off, the problem was the adjustment. If it still does not stop, wipe the valve seat clean with a cloth and replace the diaphragm. On a cistern more than ten years old, the sensible thing is to replace the whole valve, which costs €10-25 and saves you opening it up again in six months.
If instead it will not fill or takes minutes, before blaming the mechanism check the angle valve (sometimes it is left half open after a refurbishment) and the valve filter. We go into it in toilet cistern not filling or filling very slowly.
Common mistakes when fixing a push-button cistern
- Replacing the button when the seal is the problem. The button only passes the movement on. If the cistern leaks, the fault is inside.
- Not closing the angle valve. With the mechanism out, the inlet water floods the bathroom in seconds.
- Using bleach to remove limescale from the mechanism. The rubbers dry out and, if you then add a descaler, you mix two products that must never meet. Use white vinegar.
- Buying a universal kit without measuring. Check the height of the tank (from the base to the rim) and the type of overflow before going to the shop. A kit that is too long will not seal.
- Forcing the plate on a concealed cistern. A broken frame costs more than the repair. If it does not come off with gentle pressure, look for the clip or the hidden screw.
- Overtightening the plastic nuts. They crack and start to drip. Hand tight plus a quarter turn with pliers is enough.
When to call a plumber
An exposed cistern is an easy repair at home. It becomes a different matter when the cistern is concealed and you cannot find the model, when the tank or the frame is broken, when the leak shows up in the wall or when you have replaced the mechanism and the cistern still leaks. Also if the angle valve will not close, because then the main stopcock for the whole property has to be shut off.
At Manitas Costa replacing a cistern mechanism costs €60-110, with the mechanism included in most cases; fixing a tap or a small leak costs €40-70. We arrive in 20-45 minutes in Valencia, Alicante, Torrevieja and Benidorm and give you a fixed price before we start. If the cistern is cracked and has to be replaced altogether, see how to replace a toilet cistern.
More information in plumber in Valencia and Alicante and in plumber prices. To track down leaks, there is toilet cistern keeps running and, if yours is a Roca, repairing a Roca cistern mechanism. We do not touch gas, boilers or water heaters: those go to a registered installer.
Limescale and salt air: your cistern on the coast
In Alicante, Torrevieja and Orihuela Costa the water is hard, and limescale is the cistern's main enemy. It hardens the rubbers, blocks the valve filter and leaves the float stuck. Once a year it pays to open the cistern, clean the filter and rub the rubbers with white vinegar. It takes ten minutes and extends the life of the mechanism from five years to eight.
In seafront homes, in Benidorm or Villajoyosa, the salty air rusts the screws and metal springs of cheap kits. Choose mechanisms with engineering plastic or stainless steel parts. If the property is a second home and stays shut for months, leave the angle valve closed when you go and check the cistern when you return, because dry rubbers crack.
We have a plumber in Torrevieja and a plumber in Alicante for checks before the season.
Frequently asked questions
How much does it cost to fix a push-button cistern?
The part costs €8-35 depending on whether it is the seal, the fill valve or a full kit. With us, replacing the mechanism costs €60-110 with the part included in most cases. The price is fixed before we start, with an invoice including IVA (VAT) and a six-month written guarantee on labour.
Can a concealed cistern be repaired without building work?
Yes, in almost every case. Geberit, Roca and Grohe mechanisms are repaired through the button opening, without opening the wall. The wall only has to be cut if the tank is broken or there is a leak in the inlet pipe. If in doubt, send us a photo of the button and we will tell you which spare part you need.
Why does my cistern empty and then refill by itself?
Because it is leaking into the pan and the level drops until the fill valve kicks in. The most common cause is a flush valve seal that is limescaled or hardened. Add colouring and wait 15 minutes: if the pan changes colour, that seal is the culprit. Replacing it costs €5-15 and takes ten minutes.
Which mechanism is better, original or universal?
If the cistern is a Roca or Geberit and is no more than fifteen years old, the original spare fits better and usually lasts longer. Universal kits from Wirquin or Siamp suit old cisterns or ones with no spares available. What matters is getting the tank height right, not the brand.
How often should a cistern mechanism be replaced?
Every five to ten years. In hard water areas such as Torrevieja, Alicante or Elche, closer to five. If you keep replacing seals and floats every so often, change the whole kit: it works out cheaper than repeating single parts and avoids hidden leaks that push up the water bill.