Cabin Fever (2003)

Bert (James DeBello), a college student vacationing with friends in the mountains, mistakenly shoots a local man (Arie Verveen) with a skin infection while hunting in the woods. Panicking, he abandons the scene and leaves the man for dead. When the man stumbles into a reservoir, he infects the water supply, and soon one of Bert's friends becomes infected. The friends struggle to stop the contagious, flesh-eating disease while on the run from a group of ornery backwoods locals out for revenge.