Deb and Ed M wrote:
Wow - if their service didn't include dumping the tanks - they should have warned you?? The flexible poly tanks can probably survive being frozen - but all the PVC lines leading from the tanks will probably be damaged.
On edit: keep in mind that at some point, those lines will have to be thawed and they'll be leaking BAD stuff....
I know lots of folks that freeze their tanks in the mountains skiing. I don't know of anyone that has had issues. They come down off the mountain, wait a day (to thaw) and go dump.