Colonoscopy is considered to be the gold standard investigation for assessing colonic lesions; but many factors, such as the quality of bowel preparation, endoscopist, and patient factors, may affect the diagnostic accuracy and therapeutic safety. Inadequate bowel preparation has been reported in 10%-75% of colonoscopic examinations. For bowel preparation, laxatives such as polyethylene glycol (PEG), magnesium citrate plus picosulfate, and oral sulfate are consumed with water. During the bowel cleansing process, many bubbles are generated because a large amount of water mixed with mucus and bile. Endoscopists encounter a new obstacle -bubbles- even in the absence of stool. Polyethylene glycol (PEG), an orally-administered purgative, is recommended as the first-line bowel preparation regimen, mainly due to its effectiveness and safety. Simethicone (CH3)2 SiO, a silicone-based polymer, can disperse bubbles by decreasing surface tension. The hypothesis of this project is that addition of simethicone to low-volume PEG solution improves bowel-cleansing efficacy and compliance with shorter caecal intubation time and higher Adenoma Detection Rate.  Hence the primary objective of this study  is to compare the quality of colonoscopy bowel preparation of patients taking low volume PEG-Electrolyte solution(PEG-ELSE) with patients taking simethicone along with PEG-ELS.  Secondary Objective is to compare the visibility, caecal intubation time, withdrawal time, adenoma detection rate and incidence of adverse events in patients taking low volume PEG-ELS solution with patients taking simethicone along with PEG-ELS solution.