An open loop system (aka ‘pump and dump’ loop) is simply pumping water from a well or pond through the heat exchanger, and then discharging it back to where it came from.

The most common open loop system involves two wells; one that sucks the water up to the heat pump, and the other expels it back into the ground. No water is used up or harmed in any way during this process; it is just pumped through a system that adds or removes a few degrees of heat, then returned to its source. It won’t run wells dry because no water is being removed from the overall supply.