Physics puts some useful limits on things that can be applied here. All of the water used for cooling is considered wastewater, and it is generally treated chemically in a way that is difficult to process back to clean water. Water has a specific thermal mass, and we can see what hardware is being used in these data centers. From personal experience a flow rate of 1.5L/min is standard. Each rack is limited in power not by how much the supply can put out, but by what they can cool.
Even doing napkin math with the Blackwell systems that have been out for a couple of years it is as bad as they say and likely worse with the coolants and passivators going into the water.
I have advised a few water cooled systems, and did some work on Cheyenne in college. Not once was water reclamation even mentioned, it was all pumped right to sewage.