Water dispensers (or water coolers) are commonly used in both homes and offices to store and dispense drinking water. Water dispensers include “hot and cold” units, which dispense both hot and cold water, and “cold only” units, which dispense cold water only.
There are currently no national efficiency standards for water dispensers. Seven states (California, Connecticut, Maryland, New Hampshire, Oregon, Rhode Island, and Washington) and the District of Columbia have adopted standards for "hot and cold" dispensers. The state standards are equivalent to the ENERGY STAR Version 1.3 specification for water dispensers, which specified a maximum standby energy use of 1.2 kWh per day. The standby energy use (or “on mode with no water draw”) refers to the energy consumed when the unit is on but no water is being drawn. The ENERGY STAR specification also contained a maximum standby energy use limit for “cold only” units of 0.16 kWh/day. A new ENERGY STAR specification, which took effect in 2014, lowered the maximum standby energy use for “hot and cold” units to 0.87 kWh/day.
"Hot and cold" water dispensers tend to use much more energy than "cold only" dispensers because they must maintain water tanks at two temperatures in a small space. According to EPA, ENERGY STAR certified water dispensers use about 30% less energy than conventional models. The energy use of water dispensers can be reduced by improving the separation of hot and cold water, adding more insulation between the tanks, and improving the chilling mechanisms.