Pipe,
In extremely cold weather (below 10F) we will forego the water system altogether. This means the fresh tank, pump and all plumbing are air. No anti-freeze. We use the 1 gallon jugs for drinking and cooking, and do use the toilet flushing it with 100%, -40F below RV anti-freeze. We keep a couple gallons on the bathroom floor. No water in the toilet. It is pretty basic that way but is the least of your problems at zero F. Come spring you will still have a water system and pump ready to sanitize and refill. Hundreds of folks on here have followed this regimine. Of course this is with a no-basement, no heated tanks, little insulation, no double pane windows kind of rig, so it's pretty darn basic. You know, when it gets down into the single digits, F, we simply change our plans as it's too much of an endurance contest than a recreation. Now, if it's part of your gig with the pipes, just go prepared.
This was a camp at about 10 degrees F in the Eastern Sierra Nevada. Brrr. Actually looks pretty good on July 3rd. You don't see a lot of lawn chairs around. 8<)
jefe
