But you are talking about drinking water. I would be surprised if they even use that for cooling. But any non human consumption use of water (like agriculture) should happily use that water, shouldn't it?
You can use it for irrigating your lawn but not for vegetables, especially not if you plan on selling them. But 'light' gray water requires relatively little treatment before you can use it again, however this could still be quite expensive compared to just letting it go. I wonder if they've done any quantitative research on this that's public.
https://www.scaleway.com/en/blog/making-the-energy-efficienc...
That's why central heating systems that run 'low' every now and then stoke up to 60 degrees or more on the secondary circuit for tap water.
And data centers are the perfect location, endless 35 to 45 degree water. Cooling towers are the main problem for this, another is aerosols of water that has been sitting in the sun for a while, for instance in a garden hose exposed to the sun.
Drinking water from the mains is metered, so it is observable from the business perspective. Life finds a way. Heat exchangers and datacenter plumbing absolutely breed life and put things into the water that were not there when it was pumped in.
Imagine if a datacenter used a shady supplier of pipe that used, say, lead in their alloy. Do you want that datacenter grey water going into crops?
But yes, it rarely enters the building via different pipes. I'm sure that's a thing somewhere too.