In a prospective, randomized, controlled trial (RCT), two methods of performing colonoscopy will be compared in patients undergoing unsedated colonoscopy for CRC screening. We compared the water infusion in lieu of air insufflation (water method) with the conventional air insufflation method. We hypothesize that the water method (Study method) increases overall cecal intubation with comparable assessment of current experience and patient willingness to repeat future colonoscopy compared with conventional colonoscopy. In addition, the water method improves bowel preparation and increases polyp pickup rate.