A bathtub and shower diverter is a valve or switch in a bathroom plumbing system that controls where the water flows: either into the bathtub spout or up to the showerhead.

It’s used when a bathtub and shower share the same faucet setup. When the diverter is in one position, water comes out of the tub spout for filling the bathtub. When you activate the diverter, it blocks or redirects the water flow so the water is sent to the showerhead instead.

There are different kinds of diverters:

• Tub spout diverter: usually a small knob or lift-up tab on the bathtub faucet.
• Three-valve diverter: a separate handle or knob between hot and cold controls.
• Shower/tub valve diverter: built into the main faucet system.

A diverter works by changing the path of water inside the plumbing, not by increasing water pressure. If it is old or worn out, it may leak, stick, or fail to send enough water to the showerhead.

In simple terms, the diverter is the part that lets one plumbing fixture do two jobs: fill a bath or provide a shower.

A tub spout diverter is a simple mechanical valve that redirects water from the tub spout to the showerhead.

When you turn on the bath faucet, water flows normally through the tub spout and fills the tub. Inside or at the top of many tub spouts is a small diverter part, often a pull-up knob, lift pin, or rotating lever. When you activate it, the diverter partly or fully blocks the opening of the tub spout. Because the water can no longer exit easily from the spout, pressure builds in the pipe and forces the water to take the only remaining path: up the shower riser and out the showerhead.

When you release the diverter, it drops back into its normal position and water flows out of the tub spout again. The diverter usually does not “create” a new water path; it just closes off the tub outlet enough to make the water reroute.

Some diverters work better than others. If the showerhead has a flow restrictor or if the plumbing pressure is low, the diverter may not send all the water upward. A worn diverter can also leak, causing water to come out of both the tub spout and showerhead at the same time.

In short, a tub spout diverter works by blocking the tub outlet so water pressure pushes the flow to the showerhead instead.

Your shower diverter usually stops working for one of a few common reasons.

The most likely cause is wear and mineral buildup. The diverter has moving parts that redirect water from the tub spout to the showerhead. Over time, hard water deposits, rust, soap residue, or general aging can make the mechanism stick, move loosely, or fail to seal properly.

Another common issue is a faulty diverter type. If it’s a tub spout diverter, the little pull-up tab or knob inside may be worn out or broken. If it’s a three-valve system, the diverter cartridge or valve inside the wall may be damaged. If it’s a shower/tub combo with low water pressure, the diverter may seem broken because not enough water is being forced upward to the showerhead.

You may also have a clog or leak elsewhere. A partially blocked showerhead, a kinked pipe, or a worn washer or cartridge can reduce pressure and make the diverter ineffective. Sometimes the tub spout itself is the problem, especially if water still pours out of it while the shower is on.

If the diverter is stiff, stuck, or only works halfway, cleaning or replacing the diverter part is often the fix. If it’s inside the wall or the whole faucet assembly is old, a plumber may need to replace the valve or cartridge.

Turn off the water supply first. Open a faucet to relieve pressure. If the diverter is in a shower/tub faucet, remove the handle and trim plate to access it.

Check the obvious causes: Loose parts: Tighten the diverter stem or retaining nut if accessible. Worn seals or O-rings: Replace any cracked, flattened, or missing rubber parts. Mineral buildup: Soak the diverter parts in vinegar or a descaling solution, then scrub gently and rinse. Cartridge damage: If the diverter is built into a cartridge, replace the entire cartridge rather than trying to patch it.

If the leak is from the showerhead or tub spout after switching, the diverter may not be sealing fully. Clean the seat and moving parts, then reinstall with plumber’s grease on the O-rings. Avoid overtightening, which can crack plastic parts or deform seals.

If the valve still leaks after cleaning and new seals, the body may be worn or corroded. In that case, replace the diverter valve assembly. Match the exact model if possible.

For threaded connections, wrap plumber’s tape on the threads before reassembly. Restore water and test for leaks.

If water is leaking inside the wall, the pipe, or you can’t shut off the water safely, call a licensed plumber.

Bathtub diverters are the mechanisms that redirect water from the tub spout to the showerhead. The main types are:

1. Tub spout diverter This is the most common type. It is built into the bathtub spout and usually works by pulling up a small knob or lifting a lever on top of the spout. When activated, it blocks water from flowing out of the tub and sends it up to the showerhead.

2. Three-valve diverter Found in older or more traditional plumbing systems, this type uses two faucet handles for hot and cold water plus a third valve or knob that changes the water path between the tub and shower. It offers separate control and is often more durable, but less common today.

3. Two-valve diverter This system has one valve for hot and one for cold water, plus a diverter function built into one of the controls or a separate lever. It is simpler than a three-valve setup and is used in some older bath-shower combinations.

4. Shower-only or wall-mounted diverter valve In some installations, the diverter is located on the wall or integrated into the shower valve trim rather than the spout. Turning or pulling the control sends water either to the tub spout or the showerhead.

5. Tee diverter This type uses a T-shaped fitting, often in handheld shower setups, to split water between the tub spout and shower hose. It is often manually adjusted.

In short, bathtub diverters differ mainly by location, design, and how they switch water flow.