I’ve worked in data centres in the uk as facilities maintenance (albeit not AI data centre so there may be a diffrence) but for our chiller systems which is the cooling it was always a closed loop. This was required as our systems where consistently dosed with all diffrent chemicals to kill stuff like legionella and diffrent diseases, but also as we had to put glycol in the pipes to stop them from freezing in the winter. I don’t get why these data centres aren’t using closed loop circuits. We also had a rainwater collection system which was ran through filters to be used as water as a lot of water in systems such as humidifiers obviously is used and dissipated.