Back to Back installation instructions In situations where the hot and cold water inlet supplies are not in the standard positions, a reversible type cartridge can be used. A reversible cartridge will allow you fo modify the direction of the water supply to the correct orientation without changing the pipe locations. It is easy to change Ihe installation by yourself by using the following Instruction. 1. Remove the hands (1) from the body with hand. {Fig.1) 2.