Frost Line and Frozen Pipes at the Cabin

I am confused about the frost line and how it affects my concern for frozen pipes at the cabin. I would like to open the cabin this spring and am worried that I have to blow out the lines each time I leave on the weekend. I will leave the temperature inside that cabin at 45 degrees to prevent any internal pipes from freezing. What I am not sure of is:

The pump is in the cabin.
The cabin has a crawl space with no basement.
The well is about 100 ft away from the house in a shed.
There is a check valve in the house between the pump and the line in from the well.

When there is no water running and the pump is not turned on, does the water on the well side of the check valve flow back into the well?

Does this mean the water line that travels through the frost line is empty and I never have to worry about any freezing in the crawl space or within the frost line?

Why was it that the plumber never had to blow the line back toward the well when they winterized the cabin? Does gravity take the water back to the well? Assuming there is a grade downward toward the well?

Thanks! Im just concerned about frozen lines, especially underground.

Typically the freezing will take place above ground unless it’s extremely cold.
What area and temps are you experiencing ?

I wouldn’t think the line will blow back, it should be pressurized the hole length of
The well tube so you don’t have to wait for the water to be pumped up each time.

My guess it’s on of your lines installed on an exterior wall freezing?

In an urban area the water main is installed below frost line 30”-40” in most area, then enters your basement. So the line will never freeze. The water company main line is also very deep in the ground.

Thank you for the response.

Its northern Minnesota and with the cold temps this winter the frost is 3 to 4 feet down this year.

There is a check valve at the pump in the house and I am hoping no foot valve at the bottom of the shallow well. If allowing air into the line last Fall did not allow the water to flow back to the well then the line was full of water all winter and that would be bad.

The line goes through the floor of the cabin and then through a 12" crawl space before it goes into the ground. We do not heat the cabin during the winter.

I agree about the water line entering below the frost line in a normal urban area. Therefore no worries about freezing pipes.