W123 has leak accumulated on the rear passenger floor

[musikpal]

My w123 has leak that accumulate on the rear passenger floor and under the front passenger seat area. A few days ago, I first discovered puddle of water(about 16oz) after I lift a card board box that I put on the floor(Early summer, I removed the front passenger seat to reenforce the spring-and still haven't put it back on, floor mat and carpet and put a cardboard box on the passenger floor so my dog can lay on a flat surface when I have another passenger in the back seat). I cleaned the area dried. Today, after an hour of light rain in Seattle, there was puddle of water, a size of about 8 oz glass of water on the rear passenger floor and under where the front passenger seat suppose to be. But I think this leak happened a few days right after an accident. 10 days ago, I got hit-and ran-(in an elastic collision, I could have been dead had it been an inelastic one) on the driver side, by-what it look like to me- a Japanese car. The impact was mainly at one o clock to-the-right/above the wheel. And the weaker impact were at the wheel and front part of the door. The body part above the wheel was smashed leaving much bigger opening on top along side the hood (1 1/2" wide and 2' or 3' long) from the lower conner of the windshield (driver side) to approximately above the wheel. The hood had no damage, it looks and shut fine.The driver's door,however, need to be lifted vertically first in order to shut tight.
Steering was out of question...bad n not drivable
The weird thing is instead of finding water near the driver side(or at least the front floor) after SITTING in the light rain, the puddle is on the rear passenger side floor(almost opposite conner from the impacted side). Weird , or not so? Does anybody know how the water got there?
Some more info that might help diagnosing:The sun roof and windows looks totally dry and was shut tight(I shut them b4 the rain). I've been driving without front passenger seat and the floor carpet(just naked metal floor) for a while, way b4 the this flood took place. I mentioned this so that every one understand that the visibility of the whole area was not an issue here, ie. seeing 8 oz(give n take 2oz) of water is somewhat precise. There was no water spill. In side the car, the passenger floor is the lowest spot. I'll cover the impacted area with tape to see what happen when it rains.
Thanks
Kobe
Seattle

[Chad300tdt]

The rear floor is the low point in the interior. Leaks usually enter at the windshield or at the battery tray area and run to the back where they accumulate.

Remove your battery and tray and check under there. The impact may have opened a spot that was rotting. It could have also shifted the windshield causing an entry point. Use a garden hose to help you locate the source of the leak.

If it's the windshield, use Butyl Rubber Sealant between the car and the windshield gasket to seal it up. Put painter's tape on the car around the gasket to protect the paint and squeeze the sealant under the gasket just until it begins to come out. Then wipe up the excess with mineral spirits before removing the tape.

If it's the battery tray area, you may need to do a repair using POR-15 products to neutralize the rust, seal the area and repair any holes.

Good luck.