How to Troubleshoot the Plumbing in a Shower

Remove the screws from the access panel leading to the plumbing in your shower.

Locate the shower supply lines running from the wall to the shower valve. Inspect all the lines for signs of leaks. Turn the compression nuts on the supply line using a wrench to stop any leaks at the joints. Remove any leaking lines as necessary.

Turn the shower supply lines to the "Off" position at the saddle valves.

Remove the cap from the shower handle. Remove the screw from behind the cap and pull on the handle to take it off the cartridge. Lift up on the retaining clip on the cartridge with a flat head screwdriver. Slide a cartridge removal tool, available from most plumbing stores, over the cartridge. Wiggle the cartridge back and forth with a wrench to remove it from the wall. Inspect the end of the cartridge for signs of wear and replace it if necessary.

Inspect the shower valve for leaks. This is very rare, since the valve is made of fairly solid metal. If you find leaks, remove the supply lines from the valve and unscrew the valve from the wall to replace it.