Replacing a tub faucet is not much different than replacing a sink faucet. The only difference is that the tub is larger, so the faucet must be designed to fit in this space. Most tub faucets are designed with two handles for easier access, but the water lines can be accessed through a metal or plastic cover underneath the handle. The handles are usually held on by screws, and there should be two of them on each side of the faucet.