Tainted water poses an attractive danger to a thirsty traveler. A character can make a DC 10 Survival check to tell fresh water from tainted water. Most trackers know that still water holds the greatest potential for contamination, while fast-moving streams and headwaters are more likely to be fresh. A purify food and drink spell, of course, removes all doubt, and create water renders the question moot. Canny adventurers pack clean bowls or canteens with which to carry magically purified or created water and boil any water they’re forced to harvest from lakes or rivers (effectively eliminating the threat of disease). Tainted water can have any number of causes, from dangerous local plants leaching poison into the water, to a battleground or dung heap upstream, or even a simple animal corpse decaying and putrefying at the water’s edge. If a character drinks tainted water, she must make a DC 12 Fortitude save or contract filth fever. The amount of water ingested does not modify the save or the severity of the disease in any way, as a thimbleful of tainted water can have the same effect as a bucketful.
At your discretion, you can replace the standard filth fever with one of the diseases and parasites listed on the Afflictions page, such as dysentery. Wading through tainted water can also communicate filth fever, as tiny drops of the water get on the character’s hands, clothes, and face and can later be transferred to the mouth, nose, or eyes as the character moves about. It is more difficult to contract a disease in this way, though. When wading or swimming through tainted water, a character receives a +2 circumstance bonus on her save to resist contracting filth fever.
Pathfinder Chronicles: Heart of the Jungle. Copyright 2010, Paizo Publishing, LLC; Authors: Tim Hitchcock, Jason Nelson, Amber Scott, Chris Self, and Todd Stewart.