Sloshing

I noticed while tightening up my lugnuts after a brake pad/rotor change, that when the car shook, I heard sloshing. The car was off and the Emergency brake was not engaged so there was a little room to rock the car. Every time I rocked the car, it sounded like a fairly significant amount of liquid moving around. It sounded like the the noise was coming from lower in the car somewhere underneath.



The car is a 2000 Plymouth Neon with a moon roof (which doesn’t open anymore). Also, there are times that the floor behind the driver seat becomes soaked with what appears to be water. I am thinking these two things might be linked but since I am new to car repair, I need some help. Thanks in advance.

Could be easy. Radiator resevoir, windshield washer resevoir or drain line clogged to a/c box. Could be water in trunk, under spare. Moon roof has drain lines that run down the pillars and they crack and can leak.