> 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. Whether or not

> 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. Whether or not that's wasteful really depends on where exactly it's happening. If the city water is being pumped out of a fossil aquifer, that's obviously a problem. If the water is coming out of a reservoir with abundant supply, the water being "used" is merely taking a slight detour from what it would otherwise do ("river→reservoir→hvac→river→ocean" rather than "river→ocean".) There could be some energy losses in the pumping and processing of the water, depending on where it's happening, but that's not the water itself being wasted.