Colonoscopy is the current standard method for evaluation of the colon. It has an indispensable place in the diagnosis and treatment of colon diseases. Diagnostic accuracy and therapeutic safety of colonoscopy depends on the quality of the colonic cleansing or preparation. Good preparation of the bowel is necessary prior to colonoscopy, to allow clear visualization of the bowel wall and any pathology within. The proposed study is a post-marketing study in which the study device, the Angel of Water system will be used for hydrotherapy of the colon in adult subjects scheduled for elective colonoscopy, instead of standard preparation solution. The effectiveness of the hydrotherapy in comparison to the standard preparation will be defined by evaluating colon cleanliness, subject's attitude and the duration of colonoscopy procedure.