Everytime it rains really hard rain gets in the car. There is a 2 or 3 inches in the passenger side floor board.

I have the same problem with my 91' 318. Water is coming in from the outside air intake at the base of the front windshield, under the black vent covers. If the basin fills up, water enters the vent system throught the outside air intake. Solution: there is a drain line at the fire wall, easily accessible between the firewall and engine block. It drains water from the basin. It becomes clogged with dirt, and prevents water from draining. However, after further inspection of mine I noticed that during periods of HEAVY rain, even a clean drain line is inadequate to drain that volume of water and the same happens. See attached link. Good Luck

http://e30.bmwdiy.info/passenger-water-leak/index.html