Water is never "gone forever"... as
@mwj stated. It's all a part of the "water cycle". When it is "expelled" from beneath the ground into the atmosphere, it's not "lost", but it "cycles" through,
eventually, but doesn't necessarily return to the place where it had been withdrawn from. Evaporation, transpiration... they all place the water into the atmosphere.
Irrigation draws water from the below ground aquifer, and puts alot of it into the atmosphere through both. When we draw from the aquifer, use it for industrial purposes, and then send it into surface waters, alot of it gets evaporated, and the remaining liquid form typically is lost to the rivers and streams and then to the ocean eventually. It is NOT deposited back onto the area where it was drawn from, unless and until it evaporates out of those water bodies, back into the atmosphere, and is dropped in the form of rain back onto those areas that recharge the aquifer.
Now consider what happens to that water that falls as rain, if the soil is not able to absorb it. If it runs off into a creek, then a river, and then the ocean, how much of that water then was able to return to the aquifer that we drew it out of. Now add in field tile on millions and millions of acres... and how that at least partially curtails the recharging of aquifers. And what about filling and draining of wetlands?
All of these practices contribute to the limiting of access to potable water. All of these are human impacts that WE have and continue to create. Most of the time, we are not taking the COST of these impacts into account when we implement them. Absolutely, the demand for water by data centers is a big deal... the demand placed on our water resources are a big deal, all the way around.
We're all in this together. NONE of us are exempt from the responsibility to use our water resources wisely, and to do what we can, on our little piece of heaven, to help ensure that we're not negatively impacting the water cycle more than necessary. Sometimes that takes a real hard objective look at ourselves. Many, if not most of us, are often unwilling to do that.
Obviously, REUSING grey water so that it gets used more than one time, before discharging it, is a very good way to help minimize our water demand.