Water is an essential requirement in everyday life and global demand for clean usable water is increasing year by year. Therefore, developing and implementing effective water resource management and conservation strategies is vital. Generally speaking, most individuals (particularly senior citizens) prefer to use warm water when washing their hands or taking a bath. When hot water is left standing in the hot water pipe (i.e. the faucet is turned off), it will gradually cool. Consequently, when the faucet is first turned on, the water is generally allowed to run until it becomes sufficiently hot. Meanwhile, the original cooler water is simply drained away. Clearly, this approach is wasteful of both time and water. Therefore, this paper develops a green storage tank to perform a thermo-controlled water supply function. The tank is positioned between the hot water supply and the faucet and its operation is controlled by an electro-thermal thin-film heater and a thermo-controlled valve. When the faucet is turned on, the cooler water in the hot water pipe is directed into the tank. Once this water enters the tank, it is mixed with hot water stored inside until it acquires the desired temperature. The warmed water is then supplied to the faucet. When the water flowing through the hot pipe to the tank is already sufficiently warm for use, the thermo-controlled water supply function is automatically overridden, and the warm water is delivered directly to the faucet. The proposed green storage tank not only provides effective water and energy resource savings, but also provides a more convenient operation.