This is a question for you guys in Wis, Mich or Minn.

At our cabin, we winterize the pump, well and house lines. However, we do go up to the cabin in winter, but carry water for washing and to fill the toilet tank manually.

Recently, we left the cabin and like always, I drained the toilet tank, sponged it dry and then sponged the toilet itself completely dry. I add RV anti-freeze to the tank just a bit in the bottom, ran some in the over-flow and and added three or four cups of anti-freeze to the toilet bowl.

I know I added anti-freeze because I left the half filled container next to the toilet.

The next time we arrived, the toilet bowl had clear water in it and it was slushy. The anti-freeze disappeared.

No one turned on any water and or used the toilet.

What happened to the anti-freeze and where did the clear water come from?

All the supply lines are under the height of the toilet tank so water couldn't drain down from some other point.

Help me sleep at night.