Results: From the line transect method and live trap, The water monitor distribution was concentrated along the water sources in the Kasetsart University, Bangkhen campus, The area where the most water monitors were found was the lotus pond next to the main auditorium, as well as Sam Buraphachan Monument area and the men's dormitory area. From the two survey methods it was found that the area where water monitor were not found present was the pond area behind the Chulabhorn Swimming Pool and the Kasetsart University Laboratory Center for Educational Research and Development. We found the prevalence ,the population size and density increased during of water monitors is increasing every year of the study.