Well doublet ground source heating and cooling systems are rapidly becoming a popular alternative to conventional heating and cooling systems in the UK, principally because of the substantial reduction in carbon emissions that can be achieved. The sustainability of such systems, and their expected lifetime, is largely governed by the fate of the waste heat following re-injection into the aquifer. Numerical modelling using the reactive transport model SHEMAT (Simulator for HEat and MAss Transport) has been undertaken to determine the feasibility of a groundwater-based cooling scheme to remove heat generated by a UK laboratory. The proposed scheme involves the use of groundwater, pumped from a single abstraction borehole drilled into a sandstone aquifer, to feed a heat exchanger cooling system with re-injection back into the aquifer via three injection boreholes. A series of simulations have been undertaken to determine the optimum configuration of the abstraction and recharge boreholes to minimize the effects on the aquifer. To prolong the thermal breakthrough time at the abstraction well, it is concluded that the abstraction borehole must be located up the hydraulic gradient from the three recharge boreholes.