Control city water supply with 12v water valve

I did that with a normally closed solenoid valve like picture 1. I used normally closed because I wanted the water off in case of a power failure. If I wanted water during a power failure, I could always take the valve out of the system. I ran the power cord in through the slideout seal to a transformer of the correct voltage like picture 2. When I wanted water, I plugged it in. When I didn't, I unplugged it. Worked like a champ. I used a connector like in picture 3 to slip through the slideout seal with the mating end on the transformer.