Can I safely assume that water in the trunk area did not originally enter the car at the front (i.e., cowl or front windows/doors)? It appears that there is a hump in the floor behind the seats that would block it from flowing to the back. The water got into the car while it was parked for about a month, and there was a lot of rain, sometimes heavy. It was on an incline, but I don't think steep enough for the water to flow on the floor from front to back. The attached picture shows the incline. The Z was where the green car is now, in the same orientation. Thank you.

 

It is leaking in two places in the left rear corner. There is a white plastic clip that holds the bumper to the car and that protruded into the trunk. It's not all the way in, and water comes in there. It"s at top left in photo. The vent is also missing, so water splashes through the hole, even when it's just parked. Rain runs down around the tail light and splashes on other exterior parts and then through the hole. Hopefully the vent can be replaced from the inside.