Blight Water

The foetid water that indolently makes its way from the Sour Sea to the Marshes of Madness is not one to come across if you have a thirst. The water is black, putrid and if you don't see a dead animal drifting in it, chances are you will come across one should you follow it for a league or so. However, it is those desperate and foolish enough to have drunk from the Blight Water that have most to fear for the rancid taste hides a deadlier threat -- one that will not only cause a slow and inescapable death, but will see the victim rise again as a mindless Zombie.

Source
Blood in the Badlands (supplement)

pg. 11