You don't have to blow all the water out.. a little in the lines will not hurt anything. HOWEVER you do need to make sure that the pump and that little water screen/filter thing do not have water left in them... they do not drain.
2004 Chev Silverado Duramax optioned past the max. 2009 Jayco Eagle 308 RLS 765 watts of solar, 6-6 volt batteries (696 amp hour), 2000 watt (4000 surge) whole house inverter.
140 days boondocking in 2016
211/2015, 196/14, 247/13, 193/12