That and find out where it's leaking. If the windshield frame is rusty and leaking, it will need to be addressed or a new windshield may still leak. If the carpet is not currently installed, poor water around the base of he windshield to find out where it's coming in, then you can look at that area when you remove the windshield and see if it needs any work done to it.
My new windshield leaked, but that's because the installer didn't want to use silicone or butyl or whatever they use, so guess what's coming out to be resealed this spring? My windshield. At least I know the problem. I hope it's simple for you as well.