A water-water heat pump gets its heat from 3 different types of water: pumped groundwater, cooling water or surface water. Groundwater is almost always abundant and has a constant temperature between 10 and 14°C. Not to worry, groundwater will not cool or freeze when a heat pump extracts heat from it. For this type of heat pump, two wells are made at a depth of 25 to 150 meters. The first is the pumping well, the well in which the groundwater collected by an underwater pump is collected. The other well serves to release the used water back to the groundwater.A water-water heat pump can be combined with underfloor heating and ventilo-convectors, and in summer there is the possibility of natural cooling. A disadvantage is that there must be sufficient groundwater and you must get permission to use the groundwater.