Colonoscopy is a sedated procedure traditionally performed using air insufflation during the insertion phase of the procedure. Recently, the use of water method (eg, water infusion or water exchange techniques) during the insertion phase of colonoscopy has been reported to increase the proportion of patients in whom complete unsedated colonoscopy could be achieved, reduce patient recovery time burdens, decrease abdominal discomfort during and after colonoscopy, enhance cecal intubation, and increase willingness to repeat an unsedated colonoscopy. However, there has been no study on the use of water method during the training of primary care doctors or nurse endoscopists in flexible sigmoidoscopy for colorectal cancer screening.