I had a water leak that during a heavy rain storm created a pool on the floor behind the driver seat. After tearing out the seats, carpets, etc. I ran a hose over the car and discovered a flow of water running down the firewall above and behind the pedals. A previous owner had installed a stereo amplifier and ran the power cable through the firewall to the battery, the grommet/seal had come loose allowing the flow of water to run down the firewall, along the door sill and back to the rear floor board. Needless to say, I was happy to find my fix was relatively simple, good luck with yours.

Antonio