Trunk full of water

I got a 99 Ford Taurus and recently I wanted to remove the wheel to see if I can change the front breaks myself. When I opened the trunk to get the jack, to my surprise, the recess where the spare wheel is stored (below the ‘carpet’ in the trunk) was full of water, I am talking a couple of inches deep! The spare wheel itself, which is relatively new and rarely used, was completely ruptured.
I don’t know where the water could have come from, I suppose it could have been rain, but the cardboard boxes that were stored in the trunk (above the ‘carpet’) were not wet. To drain the water out, I found a big (2” x 3”) hole in the bottom of the trunk that is plugged with a rubber plug. I removed the plug and let the water drain. But now I am just puzzled. Where did the water come from? And how come there are no drain holes in the bottom of the trunk? And why did the spare wheel rupture? And how can I prevent all this from happening again?
Thanks

It had rained a couple of days earlier.

Rain can get in stealthily and through paths not obvious. I once found rainwater migrating through a small chip in the corner of a taillight lens and into the spare tire compartment. You might be able to find the path by removing the rear seatback, having a friend flood all the outside joints & seams with a hose, and looking inside with a good flashlight. Or not. These leaks can be tough to find.

I have another idea but it’s crazy. And I’ve never tried it. They make an additive for coolant that reacts to “black light” (UV). It’s to find cooling system leaks. Perhaps if you got a hose nozzle that has a car-soap bottle attached, you could filll that with the additive, follow the protocol suggested above except with a blacklight, and see what glows.

Water will enter the gap around the trunk lid and should follow the channel to run off at the rear. If the rubber flashing is twisted or trash has accumulated to block the water’s path it can run over into the trunk. Also, there is a rubber plug at the bottom of the spare tire well that can leak water in from under the car when stopped in deep water or when driving in high water.

Water can also enter through the rubber gasket around the rear window if it is slightly out of the channel. I’ve had that happen with the windshield of my Regal. When I push the gasket back in place, I don’t have a water problem anymore.

Gonna have to do a little investigative work. On my G6 just after I got it, I had water in the same place. Pulled the tail lights off etc. looking for it. Finally put the hose on it all over the rear end and the water started gushing in. It was from a wire grommet in the back behind the bumper. I had a hitch put on and when they wired it they must have not gotten the plug back in.

Just clean out the recess, remove as much from the back end as reasonable, and use a water hose all over. Rear window, seals along the trunk, tail lights, seams, etc. Its there somewhere. Why the tire blew who knows.

Quote Rod Knox "Also, there is a rubber plug at the bottom of the spare tire well that can leak water in from under the car when stopped in deep water or when driving in high water. "

Of course if a '99 Taurus were driven into or stood running in water deep enough to have water get into the trunk through the plug in the bottom, the engine’s snorkel would have already sucked water in through the air filter and hydrolocked at least one cylinder. The result is one or more bent connecting rods. I’ve seen more Tauri “ruined” this way than with those bad transmissions that everybody’s uncle seems to have experienced. I’d rather buy and sawp a used Taurus engine than a Taurus transmission. Come to think of it, I have, at least eight different times.

Don’t drive a Taurus into more than 6" of water. The car you meet may kick up a bow wave deep enough to ruin your engine. At least that’s the excuse two of my customers gave.