How to Replace a Toilet Syphon (UK)
Fit a new syphon on a lever-flush close-coupled UK toilet. Dudley, Thomas Dudley Turbo, Ideal Standard.
Thomas DudleyIdeal StandardArmitage Shanks
Syphon vs valve
UK Water Regs (until 2010) mandated syphons. Post-2010 dual-flush valves permitted — but syphons remain common on older toilets and cannot leak past the seal.
OEM part numbers
- Thomas Dudley Turbo 88 — universal replacement 315215.
- Ideal Standard Trevi — SV92967.
- Armitage Shanks Sandringham — SV05467.
Fit
Full drain — cistern off usually easier. Undo backnut, lift syphon, fit new doughnut, refit and hand-tighten only.
Frequently asked questions
- Can I fit a dual-flush valve instead of a syphon?
- Yes — but check the cistern floor thickness and opening (2" or 3").
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