I have the Injen RD CAI on my car and NEVER have any problems with water induction. Injen does extensive R&D on all of their products, and they would not overlook something like this.
By the way, I live in oregon where we get rain 95% of the year. I drive through 2 inch puddles in pouring rain doing 75 on the freeway and I never suck in water. You would basically have to be submerged in water to get any in you're intake manifold (it would have to travel a long way through the oiled filter/semi-vertical piping. By the way at this point you're feet would be wet because your car would already be flooded. So don't dogg on the Injen intake unless you have it
Good luck modding,
Kenji