I have posted this before, but if you want to actually drink the fresh water from your tanks next season, use a compressor to blow out all the lines and water heater. My first season with the boat, I did use antifreeze for winterizing the water system. The following season it was September before I was able to get the antifreeze flavor out of the water. Since them I have only used compressed air to blow out the lines and I have had NO freeze issues, even though the boat is frozen solid from NOV 1 till March 30 every year. This is season 11. The only caveat I would add is that our water tanks are only plumbed from the top, There are no pick up lines on the bottom; if there were I would have to use antifreeze in the water tanks to keep those bottom fittings from exploding.
One last point, if you have multiple water tanks, make sure that all tank selector valves are in the open position after winterization so that no water collects on top of them and then explodes them. This also goes for all of the through hull valves. Leave them open so they drain.