How to Identify a Shower Cartridge (UK Guide, 2026)
Identify any UK shower cartridge fast: Mira, Triton, Aqualisa, Grohe, Bristan. Match by valve shape, spline count and part number.
Start with the valve, not the cartridge
The fastest way to identify a shower cartridge is to identify the valve it fits. Manufacturers almost never reuse the same cartridge across ranges — a Mira Excel and a Mira Element look similar externally, but use different thermostatic elements.
Get the make and model from the valve escutcheon plate first. On Mira, the model is stamped on the front plate or inside the flow control knob. On Aqualisa, it is printed on the label behind the concealing plate.
Measure the cartridge body
Once you remove the cartridge, three numbers tell you everything: overall length, body diameter, and spline count on the temperature spindle.
- Mira 723 thermostatic cartridge: 82 mm body, 20-spline temp shaft.
- Aqualisa 022801 cartridge (Quartz/Aquavalve): 96 mm body, 12-spline.
- Triton T80 thermal cut-out: 48 mm, 6-spline.
- Grohe 47439000 (Grohtherm): 92 mm, 20-spline broach.
Cross-reference by part number
Every genuine OEM cartridge carries a moulded part number (MPN) on the plastic body. Search that MPN on PlumberSpares.com to see OEM and compatible options with next-day trade delivery.
Frequently asked questions
- Can I use a compatible cartridge instead of OEM?
- Yes for most Mira, Triton and Bristan models — compatibles from Coram, Kelda and Titan Spares are dimensionally identical. For Aqualisa Quartz and Grohe Grohtherm, always fit genuine OEM to preserve the TMV2/TMV3 approval.
- How do I know if my cartridge is thermostatic or manual?
- A thermostatic cartridge has two shafts — one for flow, one for temperature — and a wax or bimetallic element inside. A manual cartridge has a single ceramic disc.
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