During the rebuild of Christchurch, NZ they used this technique for a number of buildings, basically pumping out water with one well, then re-injecting it with

During the rebuild of Christchurch, NZ they used this technique for a number of buildings, basically pumping out water with one well, then re-injecting it with another as I understand. Essentially exploits the ground water remaining a constant temperature year around, warmer than the surface in winter and colder in summer