Tyg cocks her head to the side, but then she seems to realize what you're getting at.<br/><br/>"OH! Yea, Pearl... we could use your power to suck the damnation right outta those waters!" She brightens up and nods, and starts mumbling to herself... only to stop again. "Wait... but wouldn't that require you to actually get in contact with the water?"<br/><br/>The realization dawns on you then... In order to cleanse the river in time, you'd have to make your way further down the stream and actually come into direct contact with the tainted water... which means that the one who purifies the water has a pretty high chance of getting "poisoned" themselves.