I am thinking of our place in NW Ontario. I tried draining PVC pipes by gravity draining. That worked at times, and not at other times.
That is what I call properly done, being sure they "vent" right while draining helps a lot.
Every spigot opened, shower risers are often missed as are dishwasher control valves.
Now I use air to blow the lines, and get along fine so far.
It sure helps the job go quicker but you have to close all the valves and re-open them a time or two in the process.
Most Pex installs leave a hundred little whoop-de-doos where water will lay even when you think you have everything blown clear.
