This subject comes up every fall and spring.

The most important fact is that water EXPANDS about 9% when it freezes. Once it expands, that's it, it doesn't expand more. However, that expansion is not good for pipe connections.

It has been shown numerous times, and it happened ONCE with me, temps in the hi 20's overnight, if the daytime temps are above freezing, say in the 40s, do not cause noticeable damage to the r-pod's pipes. (Note I say 'noticeable'.) That expansion certainly did something, though. 

Apparently, there are pipe connections deeper in the r-pod, where it takes a little longer for the water to freeze because of residual daytime heat, and there we find that frozen pipes DO cause damage. 

Hello, that is why we winterize.

Being risk-averse, if I know the temperature will be below the hi 20's, I winterize. My r-pod may not freeze at mid-20's overnite, but I am not much of a gambler. That's just me. 

Ala Clint Eastwood, "Are you feeling lucky?"

 

Prepping for a fall trip into the Colorado mountains, I reflected back to my April trip to the Utah desert where we awoke to 23F and a nearly frozen water line. (after running the water for a few seconds, the sluggish, part frozen of the line came clear and the warmer water in the fresh tank prevailed. Temps then rose well above freezing in a short while.

As I prepare for this trip, just above 10,500’, I am expecting a small chance of encountering freezing temps for a few hours before temps return to daytime highs in the 50s. I expect with the hot water heater left on overnight, and the temp inside the Rpod 178 staying above 45F, inside plumbing should be safe, but the few exposed pipes under the cabin need to be addressed.
Pretty simple, I enclosed the feed hose from fresh water tank with ¾“ hot water rubber insulation tubing and duct tape. I covered the hose to the black water spray with same. Where piping was not easily covered, I put at least 1-2” of spray insulation and fill any gaps at the end of the insulation tubing. I also placed a bit of insulation behind the outdoor shower cover.

Anything else one should consider enduring 4-5 hours of mid to high 20Fs?

Also interesting, I thought I push some air into the black water spray inlet to push any water in the lines into the tank – being it seems to have its own, separate piping to the tank. To my surprise, when released the compressed air side from inlet, I got a good back splash of clear (thankfully) water. The tanks was empty, but still surprising. Does anyone know if there is a back-flow valve in place? How does one winterize that line?  

Thanks! Bob