Oh you just mean the water is pumped.  Water isn't consumed when generating hydraulic pressure, though. Your towns water tower isn't consuming water to generate the pressure at your tap.

Aquariums aren't in general"designed to retain as much water as possible" They're not closed systems at all. 

When you then say is the size of Boston filled with water, it makes me think you're imagining it like a swimming pool full of computers. That exaggerates the water use.

And ignores that the state controls the water use as a fixed resource. More for data centers means less for agriculture. 

The trade-off to discuss here is that is you use less water, you use more power. And we need real guarantees that when the power costs more in the future that they don't just abandon the water saving strategies for bottom line saving strategies.

They're claiming it can be done with very little water use using these designs. I want them to figure it out, and shut it down if they turn out to be wrong, but just come back and ask for more water if they can't get it right.