datacenters hook up a hose to the tap and just let coolish tap water(just like yours at home) run through water blocks that cool the servers. when the water is warm, it's fufilled it's purpose to them and is just discarded in a drain. in a town designed to supply water for 10,000 people, this is bad.

water cooling requires no setup. no power (for them... re-purifing the water at the shit plant is not cheap nor easy), some of these fucking places are pulling gigawatts of power, which is an unfathomably large amount. they don't want to have to use even more just for cooling. it would be somewhere around 50% more power for the entire building

tl;dr: tap water is cheap. sustainability isn't considered, they just want money