[selectodude]

Open loop cooling can work fine if they use greywater. The water isn’t potable anymore, but it goes into the sky and becomes clean again.

It’s all just a lack of imagination.

[gus_massa]

Only (mostly) water evaporate, salt and most contamination don't, so you get a brine that you must manage because otherwise it clog your heat exchangers and evaporation towers. Also, it must be returner to a river carefully to not kill all fish and life forms there.