Diverter or Cartridge? How to Tell Which Part You Need
A diverter sends water to the tub spout, showerhead or sprayer. A cartridge controls temperature and flow. They can look almost identical, and fitting one where the other belongs is one of the most common wrong-part mistakes. How to tell them apart.
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Short answer. A cartridge controls temperature and flow. A diverter only chooses where the water goes. There are three kinds of diverter: a gate inside a pull-up tub spout, a separate diverter or transfer valve in the wall, and a diverter cartridge inside some single-lever faucets. Water from the wrong outlet is a diverter problem, and a drip, stiff handle or temperature problem is a cartridge problem. Never swap one for the other because they look alike.
Which one is failing?
| What you see | Which part |
|---|---|
| Tub spout keeps running when the shower is on | Diverter |
| Shower trickles when it should be full | Diverter |
| Kitchen sprayer weak while the spout runs normally | Sprayer diverter |
| Drip from the spout or showerhead with everything off | Cartridge or stem |
| Shower will not get hot or swings in temperature | Cartridge |
| Stiff or grinding temperature handle | Cartridge |
The three kinds of diverter
1. In the tub spout. If the spout has a knob you pull up to send water to the shower, the diverter is a gate inside the spout. When it wears, water leaks past it into the tub. The fix is a new spout, matched to how it attaches: slip-on, threaded, or with a set screw underneath.
2. In the wall. A separate handle or knob that selects tub, shower, hand shower or body sprays controls a diverter or transfer valve behind the wall. On a three-handle shower it is usually the middle handle. It has its own stem or cartridge, which can look very much like the hot and cold stems beside it but does a different job. Moen’s own shower cartridge guide lists transfer-valve cartridges separately from the temperature cartridges for this reason.
3. In a single-lever faucet. Some kitchen faucets with side sprayers, and some tub and shower valves, have a diverter cartridge. It can be the same diameter as a mixing cartridge. What gives it away is the bottom: a diverter has two or more outlet ports and no hot and cold mixing.
How to tell a diverter stem from a cartridge in your hand
- Where it came from. The middle of a three-handle valve, or a separate knob, means diverter.
- The bottom. A mixing cartridge has hot and cold inlets. A diverter has two to five outlet ports, or a plain gate.
- How it turns. Diverters often turn a quarter or half turn between fixed positions, with no warm range in between.
- The markings. A part number on the body may identify it as a diverter or transfer cartridge.
Why this is the costly mistake
A diverter fitted where a temperature cartridge belongs, or the reverse, will usually go in. Then the valve will not mix, will not shut off properly, or sends water to the wrong outlet. By then it has been installed, and installed parts generally cannot be returned. Five minutes of checking beats a second trip.
What to do next
- Keep each stem with its handle as you pull them, and label them.
- Photograph the valve face before anything comes out, so you know which position each part came from.
- Send a photo of the part next to its handle, including the bottom, and a specialist confirms whether it is a diverter or a cartridge and which replacement it takes.
Related guides
- Why is my shower dripping after I turn it off?
- How to identify a shower valve with no brand or model number
- How to replace a shower cartridge
Common questions
What is the difference between a diverter and a cartridge?
A cartridge controls temperature and flow. A diverter only chooses where the water goes: tub spout, showerhead, body sprays or a kitchen sprayer. Some diverters look almost exactly like a cartridge or stem, which is why they get mixed up.
How do I know if my diverter is bad?
Water keeps coming out of the tub spout when the shower is on, the shower trickles when it should be full, or a kitchen sprayer is weak while the spout still runs. Those point to the diverter, not the cartridge.
Which handle is the diverter on a three-handle shower?
Usually the middle one. The outer handles are hot and cold. The middle stem can look very similar to the other two, so keep each stem with its handle when they come out.
Is the diverter in the tub spout or the wall?
Either. A pull-up knob on the tub spout means the diverter is inside the spout, and the fix is a new spout. A separate handle or knob on the wall means a diverter or transfer valve behind the wall with its own cartridge or stem.
Can a single-handle shower have a separate diverter?
Yes. Many single-handle showers with body sprays or a hand shower use a separate transfer valve with its own handle and cartridge. That cartridge is not interchangeable with the temperature cartridge, even from the same brand.