… As local and national opposition to data centers has grown, so, too, have concerns about their environmental impacts. Earlier this week, more than 230 green groups sent a letter to Congress, warning that AI and data centers are “threatening Americans’ economic, environmental, climate and water security.” … But as the number of data centers continues to grow across the country — and as President Donald Trump’s administration rolls back environmental protections to encourage more development — it’s worth understanding what, exactly, data centers are using water for, and how popular estimates are produced. And it’s worth having a bigger conversation about how and why we’re choosing to use water to cool data centers in the first place.