I am getting a water leak in the front passenger floor when it rains. Any ideas?

My 2000 neon would mysteriously get wetness in the trunk and rear passenger side. Couldn't figure it out for the longest time (all the seals by the doors looked fine, no holes in the bottom of the car etc). One day I saw on a forum that the tail light seals can cause leaks due to deterioration. I thought there was no chance but sure enough I pulled out the tail lights and the foam seal that goes around it wasn't sticking in all places and was partly falling apart in others!! Some people say to put appoxy or something around the bolts (when the tail light hole fills up thats where the water leaks out I think) but the idea of them being perminantly stuck wasn't appealing for me. So I just went to my local dealership and bought new seals for my tail lights. They were like $20(canadian) each and were so easy to instal. They are basically a sticker!!! Haven't had a problem since. The guy in the parts department said this was a common problem and they always have lots in stock and by me doing it myself I saved the $100 mechanic fee!!!

Most of the time if it does leak with the car just sitting. ( not driving down the road and the air conditioner drain it'snt putting water in the floor, Just sitting in the rain, then the windshield may be leaking, It can b leaking anywhere al the way around as the water will track around and end up in the passenger floorboard, How to find and fix the leak? 1). The easy way, take it to awindshield shop and tell em to fix it. They'll not look for the leak they'll just remove and reinstall the windsheild and then test it and if it don't leak they;ll charge you for the reinstall. $150 or so depends on where you live, and how nice you are to the peaple doing the work. 2). Try to find and fix the leak yourself. Sounds easy but it can be fun, Take the glove box out so you can see up under the dash have a friend spray the car with the car wash wand or garden hose. see the water coming though and decide how to add a little sealer where it's leaking and then after it dries try the leak test again if you get it great. If you don't your back to step 1). Have a pro do it.