First weekend with this unit, realizing the pump is in cabinet of bathroom and there was an empty area to the left of pump, I mounted a gallon of antifreeze ( really just to be creative )
More important and for convenience, I installed a shut off valve between water holding tank and pump, then I tallied a tee in line and another shut off, from that line I installed a section of clear tubing that can be inserted into antifreeze jugs.
So to Winterize I turn valves at water heater, then turn the two valves at pump, insert tube into antifreeze, turn on pump, open faucets..... And just in case I'm ever caught camping late in the season, I'll always have that one gallon of antifreeze to at least get out if a pinch.
In the picture the two valves I installed are orange handles.
Linear Mode
