In a Single Hole Shower Faucet, the cartridge sits inside the faucet body. It must work together with the inlet waterways, mixing structure, mounting system and handle.
For this reason, changing from a 40mm cartridge to a 35mm cartridge, or from 35mm to 25mm, is not simply a matter of using a smaller component.
A change in Cartridge Size may also require changes to the internal space, installation position and surrounding structure of the faucet body.
Cartridge Size First Affects Body Space and Product Proportions
For a compact faucet, a smaller Cartridge can provide different options for the internal layout. A larger Cartridge requires enough space inside the faucet body.
Because the cartridge sits inside the control area, its size may also affect the body diameter, handle dimensions and overall visual proportions.
If the Cartridge Size does not match the body design, the control area may look oversized.
On the other hand, a product designed around a larger body and handle should not use a smaller cartridge simply to make the faucet look more compact.
Choosing between 25mm, 35mm and 40mm is therefore also a balance between industrial design and internal structure.
A Larger Cartridge Does Not Always Mean a Higher Flow Rate
Cartridge Size may affect the available space for internal waterways, but it does not determine Flow Rate by itself.
Actual Flow Rate also depends on the internal passages of the cartridge, faucet waterways, inlet and outlet structure, flow restrictors and test pressure.
For this reason, assuming that a 40mm cartridge will always provide a higher Flow Rate than a 35mm cartridge is too simplistic.
If Flow Rate is an important selection factor, check the actual cartridge specifications and the performance of the complete Faucet instead of estimating performance from cartridge diameter alone.
Replacement is another factor that can easily be overlooked.
The Cartridge is an important functional component of a Faucet and may require maintenance or replacement during the product’s service life.
Even if two cartridges are both described as 35mm, diameter alone does not confirm that they are interchangeable. Their specific structure, fitting specifications and future availability still need to be checked.
For a Single Hole Shower Faucet, there is no absolute rule that makes a 25mm, 35mm or 40mm Cartridge better on its own.
A more practical approach is to consider body space, handle proportions, internal waterways, actual Flow Rate requirements, cartridge compatibility and future Replacement together.
The suitable Cartridge Size should follow the requirements of the specific faucet design.
