e.g. an open-loop system which disposes of waste heat through evaporation is naturally going to draw a lot more water than a closed-loop system which recycles the water. Open-loop is likely cheaper to build, and importantly, it _does_ use up a lot of water that could otherwise be going to a municipality.

So, what's the actual breakdown between these two? I absolutely _could_ imagine many datacenter operators cheaping out and using open loop cooling, particularly if building next to a source of fresh water like a river.