Description The storage tank is made of metal and is designed to hold and store the water that needs to be heated. The heating element, which is made of metal, is located inside the tank and is responsible for heating the water. When the thermostat senses that the temperature of the water in the tank has dropped below the desired temperature, it signals the heating element to turn on and start heating the water until it reaches the desired temperature. Electric water heaters are typically available in a variety of sizes, with larger tanks being able to hold more water and provide hot water for longer periods of time. They are also available in different energy efficiency ratings, which can help to save on energy costs over time.