Quick answer
A concealed cistern is a dual-flush toilet cistern built into the wall inside a Geberit Duofix frame, so only a slim flush plate shows. The frame carries the pan (wall-hung or back-to-wall), the cistern hides behind the tiling, and the flush plate is both the visible control and the access point for maintenance. The key rule: match the flush plate to the cistern series — Sigma plates for Sigma cisterns, Omega plates for Omega cisterns. Geberit concealed cisterns start around £159 at Kent Traders.
What is a concealed cistern?
Instead of a visible cistern bolted to the back of the pan, a concealed system hides the cistern inside a steel support frame (Geberit's is the Duofix range) that is fixed to the wall and built into a stud or pre-wall. Once tiled over, all you see is the toilet pan and a flush plate. It gives a clean, minimal look, frees up floor space when paired with a wall-hung pan, and makes cleaning easier.
How the system fits together
A concealed installation is four parts that work together. Buy them as a pack or build it up from components.
| Part | Role |
|---|---|
| Support frame (Duofix) | Steel frame fixed to the wall/floor; carries the pan's weight and houses the cistern |
| Concealed cistern | The dual-flush cistern itself, built into the frame behind the wall |
| Flush plate (actuator) | The visible buttons; also the access panel for the cistern |
| Pan (wall-hung or back-to-wall) | The WC bowl, bolted to the frame |
Match the flush plate to the cistern: Sigma vs Omega
This is the detail people get wrong. Geberit concealed cisterns come in series, and the flush plate must match the series and the cistern's mounting position. The two common ranges are Sigma (plate mounts on top of the wall above the pan, the most common choice) and Omega (plate can mount on the wall or on top, used where the cistern sits in a different position). A Sigma plate fits a Sigma cistern; an Omega plate fits an Omega cistern. Always confirm the cistern series before buying a plate, and check the actuation type (mechanical or pneumatic) matches.
Dual flush and water saving
Geberit concealed cisterns are dual flush: a large button for a full flush and a smaller one for a reduced flush, typically around 6 litres and 3 litres. That cuts water use compared with an old single-flush cistern, which matters for both water bills and Part G compliance on new installations.
Wall-hung or back-to-wall?
A concealed frame is most often paired with a wall-hung pan that floats clear of the floor, which looks contemporary and makes mopping underneath simple. Frames can also suit back-to-wall floor-standing pans where you prefer the pan on the floor. Either way the cistern stays hidden in the wall.
Maintenance and access
Concealed does not mean sealed in. The flush plate lifts off to give access to the cistern's fill and flush valves, which are designed to be serviced from the front through that opening, so repairs do not mean removing tiles. Geberit's components are widely available, which is one reason the system is specified so often in hotels and rental properties.
Frequently asked questions
What is a concealed cistern?
A toilet cistern built into the wall inside a support frame, so only the pan and a flush plate are visible. The cistern hides behind the tiling.
Do flush plates fit any concealed cistern?
No. The plate must match the cistern series and mounting position — Sigma plates for Sigma cisterns, Omega plates for Omega cisterns. Check the series before buying.
Can a concealed cistern be repaired once it is in the wall?
Yes. The flush plate lifts off and the fill and flush valves are serviced from the front through that opening, so you do not need to remove tiles.
Should I choose a wall-hung or back-to-wall pan?
Concealed frames suit both. Wall-hung pans float off the floor for a modern look and easy cleaning; back-to-wall pans sit on the floor. The cistern is hidden either way.
What are the flush volumes?
Dual flush, typically around 6 litres for a full flush and 3 litres for a reduced flush.
Shop Geberit
- All toilets & WCs — Geberit, wall-hung, back-to-wall, packs
- Geberit Sigma concealed dual-flush cistern
- Geberit Sigma toilet pack (frame, pan, flush, seat)
- UK bathroom refurb supplier guide