I can't speak for all the CAI's that are out there........

I've been running a NeedsWings CAI for quite a while now......at one time at the end of winter I took my car to a do-it-yourself carwash. I left the car running and proceeded to spray the hell outta the filter....not intentionally, I just forgot it was there! Fearing the worst, I pulled the end of the tube apart............not a drop of water anywhere.

If you have a NeedsWings CAI....the only way you're going to have a problem in the rain is if you drive into a lake!