My Springdale and my Outback, both had a front bedroom with the head board on the front cap. That meant both sides of the bed had those built in night stands. As stated above, on the drivers side of the trailer beside the bed adjacent the night stand area is a smaller bump out (box). In both my trailers, the water pump was located inside that box area. As stated above, both were accessed by removing screws buried in the carpet on the top. I had really fish around and pull carpet fibers to find all the screws. I got them removed and the top lifted right off. I never put the screws back in place for easier access going forward. The carpet held the top on just fine. The screw heads will NOT be a Philips head screw, it will be a "Robertson" screw head. It takes a square shaft pointed screw driver or socket style for a ratchet to unscrew it.
Robertson Screw Driver, click here.