Problems and Its Countermeasure for Hotwater Quality in Large Scale Central Domestic Hotwater Supply System : Part 2-Study on the Bacteria Multiplying Area and Thermal Environment

Abstract

Hot water supply systems have been popularized for wider application ranges in Japan. However, they have water quality problems caused by temperature change. In the previous report, from the result of the survey about hot water quality to suggest guidelines for keeping sanitary conditions, the deterioration of water quality was found in particularly central hot water supply systems, in which hot water temperature tends to be lower and the detention time in pipe tends to be longer. In this study, the authors considered the bacteria multiplying area in the pipe and its environmental characteristics. And further, the temperature change in the system, supposed to influence on hot water quality significantly, was considered through the measurement survey and the forecasting. At last the point of design and maintenance for keeping sanitary condition was suggested.