Many homes have a shower-tub combination in the bathroom. In the shower-tub combination, a knob is turned or a level is pulled to switch the water flow back and forth between the tub and the shower. For example, you turn the water on and it comes out of the faucet into the tub; you turn the knob or pull the lever and the water is diverted to the shower head. The shower diverter valve is part of the faucet assembly and diverts the water to the shower when engaged. This valve can malfunction for various reasons, making it difficult to take a shower.

Shower and bathtub
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How The Diverter Valve Works

The water pipe connecting to the tub faucet also runs vertically to connect to the shower head above the faucet. When the tub faucet is turned on, water runs directly into the tub. Pressure is needed to make the water run upward to the shower head against the forces of gravity. When the diverter valve is open, there is no pressure to force the water up to the shower head. When you want to use the shower, you turn the water on the same as if you are using the tub but also turn the knob/lever to close the diverter valve. The water running through the pipe creates the pressure needed to force the water up to the shower head because it has nowhere else to go. The diverter valve turns within the pipe, blocking off the tub faucet forcing the water upward through the pipe to the shower.

Common Problems with Diverter Valves

As tub diverter valves age, they become worn. Sediment also builds up, causing the valve to malfunction. If the valve cannot turn all the way to block the tub faucet, there will be less pressure to push the water up the pipe to the shower and water will be coming from both the shower and the faucet.

Parts in the Valve Assembly

Different parts of the valve assembly could be worn, causing the valve to malfunction. The stem screw and washer may need to be replaced. If they are worn out, they will effect the movement of the valve, causing it not to close completely. Whenever the diverter valve does not close all the way, regardless of the reason, the pressure pushing water to the shower head will be weakened and water will come out both the faucet and the shower head.

Fixing the Problem

The valve assembly can be easily taken apart and cleaned. Pry the cap off the top of the faucet handle and loosen the screw. After removing the handle, you can see the diverter valve. To take out the valve, unscrew the valve assembly from the nut located on the stem. Remove the stem screw and washer. Examine for wear and tear, replace if necessary. Using a small wire brush and vinegar, clean all the parts to remove any sediment or foreign matter. Let dry and then reassemble the valve and test it to make sure it is working properly.

Alternatives

Rather than disassembling the diverter valve and replacing parts and cleaning the assembly you could simply replace the the whole assembly. Another alternative would be to hire a plumber to fix the problem.