During colonoscopy or esophagogastroduodenoscopy (EGD), clinicians often use a water bottle to supply irrigation for the procedure. Clinicians typically use a single water bottle for multiple patients without reprocessing the water bottle between patients. This practice raises the risk of cross-contamination between patients, because the water bottle and associated tubing/connectors an become contaminated with blood,¹ stool,² or other patient fluids³ that travel back through the endoscope channels and tubing.

For auxiliary water channels with external valves, any device that is directly connected to the auxiliary water inlet (up to and including the backflow-prevention valve in the fluid pathway) should be considered part of the distal irrigation system and thus contaminated, and should be reprocessed or replaced after every patient use.

From https://www.fda.gov/media/90148/download