With a used RV you have to consider that the previous owner made some modifications to things that he did not find ideal. Perhaps he relocated the water inlet so that the hose came in under the basement, rather than a hook-up where the door is kept open a little. The water inlet will be in the same wet compartment as everything else but it may be facing down or located off to the side, etc. Sometimes it just takes some searching around. Since MoutainHigh ceased production in 2001 or so, about the only place you may find manuals is on eBay or through websites like this. Keep in mind that most all of your systems are NOT unique to MounatinHigh and most of the components are available from the specific manufacturers.