Effects of freezing on traps and toilet?

I want to not heat my cabin for weeks in the winter. This year for the first time I have plumbing. I have a valve in the well that allows all the water to drain back to the well when I shut the water off....and to be sure, I blow pressured air via a faucet. Even the pressure tank seems to empty... I hope.

What about my drains....the toilet, the traps? If the water in those freeze, do the traps and toilet break? ...or does the water just expand to a higher level when freezing, with no damage occurring?

I mistakenly bought RV Antifreeze.... I see now it is for supply lines, not waste lines. I imagine it would be effective in traps too, but wonder about effect on the septic system.

Hence my question about what will happen if I don't heat the cabin and there is water in the traps. I even thought of draining the traps and toilet somehow, but then I would have sewer gas building up in cabin, no?

Water in a toilet will probably crack the toilet when it freezes. The RV antifreeze should work. Put some in each trap in the house. They do make a version for traps, and the quantity needed should not harm a septic system.

It is listed for water lines because it is NOT toxic, but other than that you can use it anywhere you need antifreeze. You CANNOT tell water how to freeze, so it will usually expand in ALL directions. IF it can breakout by cracking something it will, otherwise it WILL expand longitudinally.

I removed a toilet a placed it outside, I thought it was completely drained but a small amount of water remained in the trap and it froze overnight and broke a palm size piece out of the bottom of the porcelain. I did not even notice initially, but I found the jagged piece lying on the ground where I had placed the toilet and when I turned it over to set a new wax ring I saw the damage. Caution!

I don't think the small amount of anti freeze in the traps will harm your septic. But if you want to, just buy a very cheap pump to remove the anti freeze in the spring. For under $10 you can get a drill pump or even a plastic bottle pump dispenser.

Do keep in mind that it is difficult to remove all the water prior to pouring antifreeze in so there is bound to be some dilution. If you do this frequently, I suggest you get one of those compressed air plungers to remove as much water as possible to reduce the amount of antifreeze you need to put down the drain.

ANtifreeze sold for use in travel trailers and motorhomes tends to be much less toxic to a septic system than automotive stuff.