One of the most important things to remember when replacing a water heater is to keep debris out of the line. If you fail to do so you may experience a leak in the shower or other faucets to your home. Debris in the plumbing system can cause several problems and can even take a few days to spot. The most common types of debris that can enter a plumbing system are wood chips from drilling holes and copper pieces from reaming the pipe. Keeping the pipe clean can be difficult when you are working on an upright supply line and need to ream the inside of the pipe. A vacuum can be used to grab the debris from this type of application. Another important thing to remember when installing a water heater is to flush out the water lines to clear the debris. If you shower or faucet is old, removing the cartridge can cause the fixture to start leaking. If you fixture starts to leak after replacing the water heater you can attempt to remove the cartridge. Once the shower cartridge has been removed you can turn the water back on which will allow any debris to flow from the fixture. If your shower is still leaking after removing the line it may be necessary to replace the cartridge or even the entire fixture.