You get much more efficiency out of the system when you lose the water to evaporation. It takes all of the heat with it. I know some data centers are experimen

You get much more efficiency out of the system when you lose the water to evaporation. It takes all of the heat with it. I know some data centers are experimenting with closed loops or wastewater systems, but while water is still priced so cheap in the US they are not in a huge rush.