I have two switches on my dash.....one cuts the ground to the boost controller and the other cuts the ground signal to the Hobbs switches to activate the WI.
Turn them both off and I still have 6 lbs boost and great power with no worries about running out of water and/or detonation.
Here you can see the two switches just above the stereo......the lights indicate low water=red, 1.0 gph nozzle=blue light, 2.0 gph =green light and yellow light= launch control activated.
I can also leave the water on since the 1.0 gph nozzle comes on at 6 lbs and the 2.0 gph nozzle comes on at 10 lbs. boost.
Each nozzle has their own separate Hobbs switch and solenoid.
No blubbering or drowning at light boost loads while climbing mountain pass grades where you need just a little boost but not full water.