I bought a 2012 JGC Laredo. Started hearing the sloshing sound about 2 months ago until this week when I thought I was at the beach from hearing the sound of the water flowing from the front driver seat to the backseat. Discarded the sunroof drains and gas tank when i drove on an incline and noticed water marks on the carpet. Saw in this forum some people mentioning the AC condensate drain. That was the exact problem. The drain is located on the center console underneath the carpet by the gear shifter, to the right of the gas pedal. The drain had come loose and leaked every time the AC was being used. The problem is that the tip of the drain hose in the plug broke or came loose and the end of it just is not long enough for the water to fall properly and causing some of it to leak back into the floorboard. To fix this, I used a smaller piece of rubber hose that would fit snug to the end of the plastic drain plug and superglued it in place, effectively extending the end of the plug. Put the plug back in place. Now the water should fall off properly and not leak back into the floorboard. Used the vehicle for some days now and no sign of water coming in again. Had to use a manual pump and drained about 5 gallons of water, removed the driver seat, side plastic board on the gear shifter, moved some carpet. Took me about 4 hours of work. Hope this helps everyone.
Heres a picture of the location of the drain:
The drain plug and some water droplets:
Picture of the plug which can be removed from the drain hose.