It may be useful to point out that the solenoid and the valve are really two different things.
Most solenoid operated valves actually work by way of an internal cylinder (with strategically placed holes) that moves back and forth inside the valve body. It operates by fluid pressure.
The “solenoid” part is an electromagnet and it simply opens and closes openings into the valve body. In other words, the solenoid operates the valve by unblocking a hole that allows fluid pressure to push on the valve cylinder and move it to a new position. No fluid pressure, no movement, even if the solenoid is working perfectly. The solenoid doesn’t push the valve cylinder into a new position directly, it simply unblocks an opening that lets in fluid under pressure and that fluid under pressure is what moves the valve cylinder.
I’ve figured that out, Bob. 
Thanks for making it clear. I need to get some fittings at the hardware store to get a column of water over it.
Check the name plate on the valve. See if it gives you the operating pressure.
You won’t get a big current surge when power is applied as the inductance of the solenoid coil will limit the rate of current change, but you will get a big voltage spike when the current is removed. This can damage switching transistors/SCRs/triacs or arc the contacts of mechanical switches. The usual cure to quench the voltage spike is to connect a reverse-biased diode across the solenoid coil (cathode to positive supply). The diode should be rated for at least the supply voltage and normal operating current, plus a healthy margin for reliability.
Water solenoids often need a minimum water pressure to keep the valve shut when de-engergised, so watch out for that too.
Yes, I had a design project in undergraduate school forming chords on a guitar with solenoids, and firing the solenoids with TTL logic chips for a guitar player who had neuro problems after a crash. Transistors failed at an alarming rate until I protected them with diodes.
I obtained fittings today, and they do indeed open with an 18 inch 3/4" pipe full of water.
Thanks, everyone!
Did you use my sure fire testing method?
Dad taught me to never look down the barrel.