Winterizing-Black Water Flush Line

[barmar]

Winterizing again but have a question. Once I've confirmed all onboard systems have pink solution in place can I then hook up the outside shower hose line to the black water flush connection and turn on the shower? This would force pink solution into the flush line/back flow preventer making sure the line is free from normal residual water. Seems to me I read about this somewhere.

[BB_TX]

That is what I do.

[dieselguy]

Or ... if you winterize with air, just screw on the blowout plug to the black tank flush fitting just like you would to the city water fitting and give her a short blast.

[Mark N.]

I just hook up an air chuck/hose bib adapter and give it a quick blast of air to push any water in it into the black tank. There is very little water held in that line.