> Similarly, I've heard of HVAC systems that just use city water for cooling. It comes in cold, dump heat into it and let it run down the drain. My grandparent

> Similarly, I've heard of HVAC systems that just use city water for cooling. It comes in cold, dump heat into it and let it run down the drain. My grandparents had a system that worked basically on that principle. Since they lived in a farming town it used irrigation water which was much cheaper than tap water.