Does an open-loop system cause environmental damage?

No. They are pollution free. The heat pump merely removes or adds heat to the water. No pollutants are added whatsoever. The only change in the water returned to the environment is a slight increase or decrease in temperature. Some people are concerned that open-loop systems contribute to the depletion of our ground water resources. This issue is not critical in some parts of North America because of abundant supplies of ground water.