Solenoid valves for water supply
Asco is probably the biggest name in solenoid valves in the US and Canada with their "Red Hat" line of electrically operated valves. Look in your yellow pages under valves and see if any of the companies there advertise that they sell Asco.
I'd recommend against what you're wanting to do. You're just adding more potential possibilities of a malfunction into a critical operation. It's critically important that you drain water pipes to prevent them from freezing in winter. If you stand there and open a valve and see the water draining out, then you KNOW the pipe is empty. If you flip a switch, you don't have that 100 percent confidence any more. The motor might not have operated cuz a badger gnawed on the wiring, or whatever.
If it was me, I'd still be going around to check that everything that needs to have been done was done, and that's going to take almost as much time as doing it all manually anyhow.
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