How to Identify a Tap Cartridge (UK Guide)
Identify UK tap cartridges by diameter and spline: 35 mm, 40 mm, 25 mm ceramic discs. Bristan, Grohe, Franke, Reginox, Ideal Standard.
Two families: ceramic disc and quarter-turn
Every modern UK tap uses one of two cartridges: a single-lever ceramic disc (mixer taps) or a quarter-turn ceramic headwork (pillar/bib taps). Get the family right first — the swap won't work otherwise.
Measure the cartridge diameter
Mixer cartridges come in three UK sizes: 25 mm (basin taps and compact monoblocs), 35 mm (most kitchen and basin mixers), 40 mm (heavy-duty and commercial mixers such as Franke Olympus).
- Bristan Prism / Cascade — 35 mm cartridge, 20-spline stem.
- Grohe Eurosmart — 46374000 cartridge, 46 mm outer with 35 mm ceramic disc.
- Franke Olympus — 133.0069.517, 40 mm.
- Ideal Standard Ceraplan — A960478NU, 40 mm ceramic disc.
Quarter-turn: 1/2" vs 3/4"
Traditional pillar taps take a 1/2" or 3/4" ceramic headwork. Count the number of turns on the old headwork before removal — a true quarter-turn stops firmly at 90°. A half-turn ceramic headwork gives finer flow control but wears the seal quicker.
Frequently asked questions
- Can I fit a 35 mm cartridge to a 40 mm tap body?
- No. The cartridge locates on a shoulder cut to the body diameter. A 35 mm cartridge in a 40 mm body will leak from the base.
- Are hot and cold cartridges different?
- For quarter-turn ceramic headworks, yes — the rotation direction is opposite. Fit anti-clockwise-to-open on the hot side, clockwise-to-open on the cold side.
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