I'd like to leave a vacant house in Northern Minnesota for the winter with no utilities at all (so it will get to -20F at times). I shut off the curb stop valve and confirmed that water is completely stopped. I used a compressor to blow all piping (and everything connected to the piping, like the water heater) empty. There probably are "specks" of water left but that should not cause a problem.
But, I could not blow the piping between the curb stop and the first Y-branch inside the house, so I imagine that there is retained water there. Is there a way to blow this section empty?
I also flushed all toilets. Am I taking any structural risk if I don't fill the toilets with antifreeze? Please assume that I don't care about sewage odor (I will just air the house out afterwards). I wonder if people are adding antifreeze because water condenses on the toilet bowl over time and refills the p-trap.
Finally, if I blow that section to the curb stop and use antifreeze in the toilets, am I taking a big risk? The biggest risk I see is that the curb stop valve could freeze and damage, but it seems I can just tell the water company of my plans and they would take responsibility to keep an eye on the curb stop. Am I missing some other big risk?