UK trade guideToilet & Cistern 4 min readUpdated 9 July 2026

How to Replace a Geberit Flush Valve Seal (UK)

Fit a new bell seal on Geberit UP320/UP720 flush valves. Cures constant trickle into the pan.

Geberit

Symptom

Trickle into pan hours after flushing. Blue-dye test in cistern shows blue in pan.

OEM part numbers

  • Full flush valve — 240.638.00.1.
  • Bell seal service kit — 240.045.00.1.

Fit

Remove plate. Rotate flush valve 45° anti-clockwise, lift out. Replace bell seal, refit with slight silicone grease on the flange.

Frequently asked questions

How often does the Geberit bell seal fail?
7–12 years typical. Hard water areas reduce to 5–7.
Shop the spares

Browse toilet & cistern6,230 live parts.

View Toilet & Cistern