I have Puddles inside my car!?

A few weeks ago I had a mechanic put in a new Fuel Pump in my '96 Buick Skylark. When I picked it up there were large puddles of liquid in my car, but I figured it was just as winter was ending, so maybe all winter people's feet had dragged in snow that had melted and then froze again under the mats, which was just thawing out again. But every time I suck out the water a few days later its back again. Lately it's been getting worse and no one seems to know why I have puddles in my car when the windows are up and it's been fairly sunny out. I do have a loud exhaust and several things I need to get fixed (struts, brakes, and shocks). If anyone out there knows what might be wrong I'd be very grateful to find out what's going on.