My system is based on a well in the ER. I have a well pump that recirculates the water...
I agree with everything 2biz said, but having been stung I take the precaution -
I have the same setup as nuphoenix, HUGE money saver to be weeping the same water over and over!
I have it set up with a weepmizer and NO solenoid.
However, yes, years ago the power went out and the entire wash froze. Of course it was a sunny january saturday, and I was out of town coaching a soccer tournament.
So I added a city water feed into the weep system thru a second NO solenoid, powered all the time to keep it closed, not thru the weep mizer. That way when the power is working I weep recycled water, when the power goes out I weep city water.
I added a third input for weeping hot water, I've chosen to do that on a few occasions.
To manage that "complexity" I built a small manifold. Gauges, ball valves, solenoids, etc. Sounds complex, but not really, I pretty much never have to touch it. I think I have a pic somewhere...