Groundwater is the best heat source in cold climates in terms of seasonal system efficiency, as its temperature is almost constant throughout the year, between 13 and 16 °C on average. Hydrothermal heat pumps extract heat from groundwater and raise it to the required temperature to deliver it to the room to be heated. The groundwater is lifted by a hydraulic pump immersed in a withdrawal well to come into contact with a heat pump evaporator that extracts a few degrees, before being returned to the re-injection well (or surface) without any chemical modification or pollution. The few degrees extracted are then raised through a thermodynamic cycle, powered by a small amount of electricity, to the temperature required by the environment to be heated.