There should be a drain hole in the locker, sometimes the sac will block it and trap some water in the lockers. Once you empty the sac you can move it around a bit and let the water drain into the hull.

Leaving the water in there really won’t hurt anything but you will end up with some mildew on the sac and in the locker.

Good luck, E

PS – you also may want to check the sac for leaks ie; pin-holes, connections, fittings, plugs, etc.