The authors carried out a measurement about the consumption and the operating temperature of hot and cold water of the three guest rooms in a city hotel. The purpose of this study is to develop the calculating method for hot and cold water consumption in the guest rooms of city hotels by the Monte Carlo simulation technique on the basis of the analysis of hot and cold water usage. In this paper, the overview of this measurement and the analyzed results were shown, and the authors considered about the characteristic of changing tendency for the hot and cold water consumption by the guest's attributes. Moreover, the detailed fixture uses of hot and cold water which were measured by the interval of 5 seconds were analyzed, and a calculation model of hot and cold water consumption applied for the simulation technique was proposed.