There is a finite amount of water on this earth, and it never changes.
Evaporation and evapotranspiration put water into the air, which turns into rain, which fills our lakes, river, aquifers, etc. We treat and use it, send it to a plant for waste treatment, which sends the treated water into a creek, lake, river, etc.
Most evaporation occurs from the oceans, but the salt stays so only fresh water falls from the sky.
Nuke plants use water for cooling, much the way traditional plants do, and what data centers do. Many businesses use water for cooling.
It always gets returned, no matter what.
