Seeking Source of Lake!

I have a 2000 Ford Focus. Two weeks ago we had some really heavy, wet snow. I went out to my car expecting to spend time removing it from the exterior - imagine my surprise when I opened the front passenger door and discovered a small lake on the floor (I bailed the water out with a cup)! I could see water streaming in from below and to the left of the glove compartment, but couldn’t determine its path from the exterior to there.

I had the windshield replaced in early February so I assumed this was the problem. I took it back to the glass experts - they apologized profusely, spent a few hours with my car and returned it at no charge with a “no car washes for 24 hours” statement but no information confirming the source of the leak. Needless to say I was extremely upset when we got heavy rain this past weekend and the lake re-appeared.

I’m taking it back to the glass folks but with decidedly less confidence. A few questions:

1. Could the source of the leak be from something other than the windshield?

2. Should the glass folks be able to conclusively determine if the windshield is the source?

3. Could there be some internal damage that’s not as visible as a sopping wet floor?

Many thanks for any assistance!

Yes to all 3.

You might try running water from a hose onto the windshield yourself to duplicate the leak. You will need to find a way to keep it from running all over the windshield. Maybe you could use a plastic sheet to cover all but a 6-inch wide strip of the windshield while you wet it. Tape the plastic to the windshield to keep water from getting under it. You will need to run the water for some time to generate enough flow inside to make it to the floor. If you can’t find the leak on the bottom, try the sides and finally the top. If there is still no leak, it isn’t the windshield.

While I suspect it is the windscreen, there are other possibilities.  

Water comes in those vents that are right in front of the windscreen.  If the drain in the are under the vents is clogged, it then usually finds a way into the cabin.  

 If you have a sun roof, that also may have a clogged drain or two and water is coming in that way.

Check the AC evaporator drain tube. If it’s clogged (glass fragments, perhaps?) or disconnected rain or snow melt will flow into the car through the ventilation system.

Clogged sunroof drain tubes are another source of leaks.

This is just a possibility: Look closely at any wiring that exits the inside of the car through the firewall or through the body under the front passanger side fender. The rubber grommets can deteriorate and allow water to come in and drip down the wires and onto the floor. I had a car in which I had to remove the front fender to replace that rubber grommit in order to stop the leak. When finding this leak- To see the water leaking in I had to have a buddy stand there with a water hose pouring on the car, then I had to have my back on the floorboard with my head up under the dash and a flashlight. Even then all I could see was a tiny dribble running down the metal to the carpet on the floorboard~

Lake or leak? They are quite different.

If you have ruled out the windshield as the source of the leak, take a look down the firewall and look for a welded seam that is a collection point for dirt, salt and grime. Check that seam for rust holes that could allow water in. How to fix would be another matter but might be able to caulk it up for a while.