Water source heat pumps take in water from a body of water, absorb heat from it in the pump, transfer that heat to the heating and hot water circuits of a building, then discharge it back.

Requires: Suitable aquifer or surface water source.

Since water source heat pumps circulate water then return it, they are sometimes confusingly referred to as open loop ground source heat pumps.

There are two types of water source heat pump, groundwater and surface water. Groundwater systems involve drilling a borehole to an aquifer, similarly to borehole ground source heat pumps. Groundwater source heat pumps extract water, compress it, use it for heating, then discharge it back to the aquifer down a second borehole. Surface water source heat pumps abstract water from a river or lake and discharge it back downstream.

Water source heat pumps are subject to regulation, so it is important to make sure that the required planning and environmental permissions are obtained.

Typically, water source heat pumps are the most efficient kind of heat pump.

Ground Source Heat Pump Association, Water Source Heat Pumps. Available from: https://www.gshp.org.uk/WSHP.html [Accessed 26th January 2021].