Interior(front floor area) water leakage problem when it rains.

What is your question?

When the vehicle is on a level surface, during a rain(no problem), but if parked, on a slant or if I am operating the vehicle while it is raining the floor (passenger and driver side) accumulates water to the point I have to use a shop vac to get it up. I am clueless as to what the problem is, or how to repair it. Help!