Do we worry about the Gray and Black tanks?  I mean other than draining?  

I've heard of others doing this.  But there may still be a chance of water collecting somewhere.  If you use the antifreeze, you can leave whatever you pump through in the black and gray tanks.

Maybe someone else can comment on the compressor idea, as I've not done that.

Originally posted by Mirado It would be tempting to let it go at that - a dip into the upper 20s might not be a problem, but it takes only one dip to near 20 or below and something's going to freeze.  Get some RV antifreeze and run it through all of your pipes (bypass the water heater first, but do drain it) sink traps, and tanks and leave it in until spring.  Unless you plan to camp in the winter.  You could leave a small electric heater running inside the pod, with the plumbing exposed as much as possible...but that won't protect the the exposed lines underneath.

One caveat to the above is that if the daytime temps are above freezing AND if heat is running in the 'Pod, a dip into the low 20's is probably okay, especially if one insulates the line leading from the tank to the pump as that is the only really exposed part. The tank itself will not freeze overnight if it has a significant quantity of water in it, but if it is empty or nearly so, there is not enough mass of water to keep it from freezing. In that case, draining and winterizing is better.

We've been through camping with water in freezing overnight temperatures. Extended freezing temps always require winterization.