It's so easy your going to kick yourself.
First you want to open your low point drains (one at a time ) and blow air through the city water inlet (40 PSI ).
Close the low point drains and then insert the tube that's attached to your water pump into a gallon of antifreeze.
Turn on the pump and turn on the say bath cold water till it runs pink then do the shower cold then kitchen cold and outside shower.
Do the same to the hot line and while it's still under pressure open the low points for just a second or two just in case there's a little water in those lines.
Now this step is important also, even thou you think your fresh water tank is empty you should check under the trailer and check that drain line because they usually sag and hold water just make sure it's empty or else if it freezes that plastic drain valve will crack and will need replacing just when your ready to go camping next season.
2010 Jayco Hybrid EXP21M
2013 Toureg TDI