Traditional water heaters, often referred to as tank water heaters, are appliances that store and heat a large volume of water for household use. They typically consist of an insulated tank that can hold anywhere from 20 to 80 gallons of water. When hot water is needed, it is drawn from the top of the tank, while cold water enters the bottom to be heated. These heaters use either electricity or natural gas as a power source to heat the water. While they provide a steady supply of hot water, they can be less energy-efficient compared to newer technologies like tankless water heaters, which heat water on demand.