Water Under Rear Seats

I have an 04 hatchback and I find water in the sockets for the rear seat locks after driving in the rain or going through a drive thru car wash. Any thoughts on what's happening? And how would I fix it? I was thinking that I might be able to use some silicone caulking to seal the sockets themselves, but I'm worried that it's just going to find a different place to pool.

Got any pictures of the area you're talking about?

Is there water anywhere else that may lead to where its coming from? If not, tear some stuff out of the car, and hit it with a garden hose with someone inside to watch where its coming in.