Dear Dave, Run off water will collect and accumulate in the splash area during use, but these inflatables are not designed to retain water over extended periods. If you turned off the water, eventually the water would drain out through the seams at the bottom of the splash area. This draining occurs slowly over time. If you'd like to drain the splash area, you can you can push down on the rim around the splash area to let the water out that way. Alternately, turn off the water and the blower. As the inflatable deflates, the water in the splash area will run off naturally. Sincerely, Blast Zone Support