UK trade guideToilet & Cistern 3 min readUpdated 11 July 2026

How to Replace a Geberit Sigma21 Flush Plate (UK)

Swap a Geberit Sigma21 concealed-cistern flush plate in a UK bathroom. Dual-flush levers, seals, adjustment.

Geberit

Identify

Confirm your Geberit frame series — Sigma21 plates only fit specific in-wall carriers. Look on the inspection window for the frame's date-stamp and part number.

Remove the old plate

Pull the Geberit Sigma21 plate away from the wall (magnetic or clip-on). Disconnect the two flush levers or pneumatic tubes from the top of the cistern.

Fit the new plate

Adjust the Geberit Sigma21 lever rods to length. Reconnect, refit the plate. Test full and reduced flush volumes (6 L / 3 L standard UK).

Frequently asked questions

Will the Geberit Sigma21 fit any concealed frame?
Only Geberit-brand frames. Cross-brand fitting rarely aligns.
Do I need to isolate water?
No — the plate is external; you only touch the flush actuators, not the fill valve.
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