I was curious about this a while back. My cursory research showed that these facilities are actually phenomenal at recycling water to the point that they're not actually guzzling water at the rate you might expect.

...deputy spokesperson Nina Kao said via email that “approximately 65% of the water used in the Arizona fab will come from TSMC’s in-house water reclamation system...

https://www.azcentral.com/story/opinion/op-ed/joannaallhands...