If you've used the sponge before, you're well aware that it soaks up and holds back a hefty chunk of water: a 3 unit cube, if I remember correctly. This makes it ideal for clearing out flooded tunnels, as you've probably discovered. However, what many may not realize is that sponges, when strategically placed, can prevent floods.
What I've begun to do is to go back through all of my underground tunnels and place sponges, hidden behind walls, to hold back any unfortunate and accidental floods. I've placed them at corners, at entrances, intersections and, for long tunnels, at halfway points. This way, in the now unlikely case a flood occurs, the damage is localized and can be quickly cleaned up in literally a few seconds.
This is just an example of a one-unit wide by two unit tall (the sponge is one unit about floor level) tunnel. As you can see, any unfortunate spills will be soaked up and stopped faster than you can saw Bounty the Quicker Picker Upper. In addition, because the sponge is hidden, aesthetics are maintained for any themed maps.