Add a 1 way anti syphon valve into the system and you wont have to worry about water leaking out.
CNBLOW
You should use nozzles at admit a fine mist of water onto the intercooler, that way the water will cool the intercooler better as it will evaprote quicker. The stock wiper pump may not be able to produce enough pressure to drive the misting nozzles tho.
I used to work with water intake cooling on gas turbines a few years ago