Yes, the water needs to be turned off in order to replace a shower cartridge. Here are the steps:
• Turn off the water supply valves – located on either side of the faucet.
• Open up your shower handle and inspect for any debris or damage.
• Remove and replace the cartridge with a new one.
• Reassemble all parts of your faucet before turning back on the water supply valves.
Remember, it’s important to turn off both sides of the valve when replacing a shower cartridge; otherwise you may experience major flooding!