looking thru the online manual it says to drain waterlines , tanks, toilet and water heater and leave the tank plug out before suppling air pressure. It says not to bypass the hot water heater (also says bypass is in kitchen sink area?). If so, How does the hot water supply lines get blown out?

We are new to this site and new to owning a 1987 Minnie Winnie 426 Class C. Only 27,000 miles on her but we plan to put much more in the near future. I hope to learn a lot from all the members on this site as we've never owned motorhome. So kind of wet behind the ears. Our future questions will address maintenance on Ford 7.5 L 460 engine and also camping areas of interest that don't mind an older but well kept rig in their park. Thanks and will keep you posted on progress as we give her some TLC....