Yeah -- I had looked into a solenoid, but, correct me if I'm wrong, the way they generally work is that they are normally closed. Then when you run current through them, they open. This means that the solenoid would be "hot" (or on) for the period of time that water is being used... sometimes a week, sometimes a couple days...

Either way, and again correct if I'm wrong, a solenoid is required to be "hot" to hold the opposite position it is stated to be "normally" (i.e. normally closed no juice when closed, and hot when open and visa-versa)

Do I have that right?