Prior to blowing out the system with air I drained the hot water heater with the pressure release valve spigot, into the engine compartment bilge. The bilge got shop vac'd and after the water was sucked out I spilled a little pink anti-freeze in for good measure so the sump pump wouldn't freeze.

By the time I was done the whole system was pretty empty. If there were any water plugs remaining in the lines, they were small and collected after I was done. I'm not that worried about a small amount of water in a flexible vinyl hose, because that will allow expansion. I get concerned about rigid plumbing, fittings and tanks.

The pink antifreeze is a breeding ground for microorganisms and mold. It pollutes the lines with propylene glycol. In the past it's always taken me several tanks to get rid of the taste and odor. Not this time. Yes they say it's non-toxic but it can't be good for you. It's very closely related to ethylene glycol which is engine antifreeze and is deadly poison. That only takes a couple of tablespoons to shut down your liver permanently.