Spc. Sean Tynes, a Preventative Medicine Specialist of the 988th Medical Detachment from Round Rock, Texas, tests for chlorine residue, alkaline and acidic levels in the water buffaloes to ensure that it is safe for soldiers to drink during Combat Support Training Exercise (CSTX) 91 13-01. The CSTX gives participating units an opportunity to rehearse military maneuvers and tactics such as base security, convoy operations, and battle reaction drills during simulated enemy attacks as well as apply their military occupational specialty skills in a theater of operations. The exercise provides realistic training to units to successfully meet the challenges of an extended and integrated battlefield.