Regulating Data Center Water Use in California — Marie Grimm, Nell Green Nylen, Michael Kiparsky (2026)

This report examines how expanding data centers—driven by AI growth—are increasing water demand in California. It analyzes usage patterns, regulatory gaps, and policy options, arguing that improved transparency and governance are urgently needed to manage growing environmental and resource impacts.

1. Scale & Environmental Pressure

2. Knowledge & Transparency Gaps

3. Technical Drivers & Trade-offs

4. Governance & Regulatory Gaps

5. Solutions & Policy Opportunities

6. Urgency & Future Risk

⭐ Star Facts

• Data centers are among the top 10 water-consuming industries in the United States
• California has at least 270 data centers, with numbers expected to keep rising
• Hyperscale data centers are projected to use ~150 billion gallons of water (2025–2030) → equal to the annual water use of 4.6 million U.S. households
• California data center water consumption is projected to grow from 351 million gallons (2019) → 1.12–1.75 billion gallons (by 2028)
• Individual data centers can use tens of thousands to hundreds of thousands of gallons per day, depending on size and type
• In some cases, ~76–79% of water used is consumed (not returned to the source)
• About one-fifth of U.S. data centers are located in water-stressed regions
• There is no comprehensive regulatory system for data center water use in California—only a fragmented patchwork of policies
• Most data center water use is for cooling, making design and technology choices critical
• Lack of reporting requirements leaves policymakers and communities without clear data on water use and impacts

🧠 Conclusion