A:Answer Thank you for connecting with us! The inlet line is located on the rear of the refrigerator, at the bottom. For more information about the size, as well as how this unit interacts with a RO water system, we highly recommend checking out page 37 and 40 of this unit’s “Use and Care Manual”. We hope this helps, and if you have additional questions, please reach out to us. Wishing you well – Matthew@GEA