You can mount them virtually anywhere that's close to a water source. Mine is in the laundry room. I have a wye coming off the cold water hookup with a valve on each side. When I want to make RO/DI water, I turn on the valve that the RO/DI unit is hooked to (washer valve stays on). I stick the waste water line in the washer so that it's not actually being wasted. I don't have an optimal setup yet, as I just fill up 4g water jugs from a drinking machine, but that's pretty much all there is to it. You can use a python for draining, but not for filling.