I'm pretty sure your water lines are INSIDE the trailer, under the sink, under or behind the refrigerator, at the back bottom of a lower cabinet, under the couch, etc. (I've just given you my water line locations, but I have a smaller trailer.) However, I think you'll also find two drain valves, one in the hot water supply and the other in the cold water supply that runs from the pump to the sinks, shower and toilet. If those drain valves have been bumped open, water will come out under the trailer. My valves are accessible through a door on the outside lower half and the valve handles need to be pointed UP to close off the drains. When I first had the trailer, I thought they should be down parallel to the water pipes and that was the drain "open" position.
So check for the drain valves and if they are fine, look for leaks anywhere along the piping. You could probably pull new PEX tubing through with a snake if you needed to replace any of it.
Hi-Lo 1707T - Tire Minder TPMS on Tow Vehicle and Trailer, 300W Solar Battery Charger, Equal-i-zer WDH
2014 F150 Platinum 4x4 3.5L EcoBoost SCrew