How to protect Waterpump from Frost

Hi *,

I am thinking about a solution to protect my water pump from frost. This winter, I was too late to drain it and it was torn in half. It is not connected to a tap, but to rain water tanks.

A perfect use case for an automation.
But how?

The pump has two 3/8 " sockets, one to drain it and one to refill it.
My Idea is to use 24VAC valves with 3/8" threads. But I didn’t find any.
First question, can someone recommend such valves?

Draining would be easy: just open the valve when the temperature drop below zero degrees.

But how would I automatically refill it?
I would need some small water reservoir, which itself is protected against frost.
How would I do that?

Looking forward for any suggestions!

Thanks,
Ck