The Ecokettle allows its user to select exactly how much water they need to boil. The water is measured in cups 1-8 and is released into a specific heating chamber. This saves time, electricity and (they boast) water. The water saving is not as significant as the energy saving however I guess a fair amount of water is lost due to steam in a kettle. Do people discard unwanted boiled water from a kettle? We don’t. It just gets boiled again when we next need hot water.