Growth in Artificial Intelligence (AI) and other cloud-based computing services is driving an unprecedented expansion of data centers across the globe. As data centers have become much larger and more concentrated, concerns about impacts on water and energy systems have intensified. This issue brief summarizes what we know about data center water use and addresses common misunderstandings. While data centers represent a relatively small proportion of global or national water use, data center water use can be locally significant, especially in water-scarce and rural areas. The lack of standardized reporting on the number, size, location, and water use of data centers makes it difficult for communities, water managers, and decision-makers to understand and adequately address potential impacts. 

1. Data centers are expanding into new areas, including water-scarce and rural parts of the United States. This expansion can strain local infrastructure and create challenges for more capacity-limited operators. 

2. Data centers use water directly and indirectly. Indirect water use is typically much larger than direct use but is often ignored in water use reporting. 

3. While data centers represent a small share of global and national water use, their impacts are experienced locally. Water withdrawals range from 270 gallons to 3.9 million gallons per day. For a typical facility, 74% of the water withdrawn is consumed and unavailable for other uses within the water basin. 

4. The water demands of large data centers differ sharply from most commercial buildings, and these differences may create unique challenges for municipal water systems serving them. They withdraw far more water than most commercial water users; concentrate their use during the hottest periods; and consume a much larger share of the water withdrawn. 

5. More and better water and energy data are needed. The lack of standardized reporting on the number, size, location, and water use of data centers makes it difficult for communities, water managers, and decision-makers to understand and adequately address potential impacts.