Data Center Water Use: What Residents Should Ask

This guide explains how data centers consume water—primarily for cooling and on-site power generation—and gives local residents a practical list of questions to ask at community meetings, public hearings, or through public records requests. Understanding the basics helps you evaluate a facility’s environmental impact and hold operators accountable for water stewardship.

What You’ll Need

• Basic knowledge of your local water utility (source, rates, drought status)
• Contact information for your city or county planning department
• Access to public records request forms (usually online)
• Notepad or document to record answers

Step-by-Step

1. Learn the two main water uses. Data centers use water primarily for cooling (evaporative cooling towers, chillers, or direct-to-chip cooling) and for on-site power generation (if they have backup diesel generators, water is used for exhaust scrubbing). Some facilities also use water for humidification and domestic purposes (restrooms, landscaping).
2. Understand the cooling system types. Ask whether the facility uses evaporative cooling (which consumes water through evaporation), closed-loop cooling (which recirculates water but still loses some to blowdown), or air-cooled systems (which use little to no water but consume more electricity). The type determines the water intensity.
3. Request the water consumption figures. Ask for the facility’s annual water usage in gallons or cubic meters, and the water usage effectiveness (WUE) metric—a ratio of water used (in liters) per kilowatt-hour of IT energy. A typical WUE is 0.2–1.0 L/kWh for evaporative cooling; air-cooled can be near zero.
4. Check the source of water. Is the facility drawing from municipal supply, groundwater, or recycled wastewater? Ask if the water is potable (drinking quality) and whether the facility is required to use non-potable sources where available.
5. Ask about wastewater and discharge. Cooling towers produce blowdown (concentrated minerals and chemicals) that goes to the sewer or stormwater system. Ask if the facility treats its discharge and if it holds any discharge permits.
6. Inquire about drought contingency plans. Does the facility have a plan to reduce water use during droughts? Can it switch to air-cooling or use stored water? Ask if there are any mandatory restrictions that apply.
7. Review the environmental impact report (EIR) or permit. For new builds, the local government often requires an EIR that includes water supply assessment. Request a copy and look for the sections on water demand and mitigation measures.
8. Attend public meetings and ask directly. At city council or planning commission hearings, ask the operator to state the projected water use, the source, and the expected impact on local water rates and supply. Record their answers.
9. File a public records request if needed. If you don’t get clear answers, submit a public records request for the facility’s water use reports, permits, and any correspondence with the water utility. Be specific about the documents you want.
10. Follow up with the water utility. Your local water provider can tell you if the facility is a major customer, whether it has a special rate, and what percentage of the utility’s supply it consumes. Ask about long-term supply projections.

Common Mistakes

• Assuming all data centers use the same amount of water. A hyperscale cloud facility can use millions of gallons per day, while a small colocation site might use a few thousand. Always ask for specific numbers.
• Confusing water withdrawal with water consumption. Withdrawal is the total taken; consumption is the amount that evaporates or is otherwise not returned. Consumption is the more important figure for water scarcity.
• Overlooking the power-water nexus. If the data center gets electricity from a fossil fuel plant, that plant also uses water. Ask about the energy mix, because renewable sources like solar and wind use far less water.
• Not checking the drought resilience of the water source. A facility in a water-rich area may still strain a local aquifer during dry years. Ask about the source’s vulnerability.
• Assuming that a low WUE means low total water use. A very large facility with a good WUE may still consume more water than a smaller facility with a poor WUE. Always look at absolute numbers.

Tips

• Ask for the water usage in gallons per day (or per hour) and per year—this makes it easier to compare with your own household use (average US home uses about 300 gallons/day).
• Ask if the facility has a water recycling system, such as using cooling tower blowdown for irrigation or treating wastewater for reuse.
• Look for commitments to water positivity—some operators aim to return more water than they consume. Ask if they have such a goal and how they measure it.
• If the facility is in a water-stressed region, ask about the use of air-cooled chillers or adiabatic cooling (which uses water only during hot periods).
• Bring a friend or neighbor to public meetings—strength in numbers can lead to more detailed answers.

Troubleshooting

• If the operator says “water use is confidential”: In most jurisdictions, water use data for industrial facilities is not confidential—it’s part of public records. Politely insist on a public records request.
• If you get vague answers like “we use water efficiently”: Ask for the specific WUE number and the total annual consumption. If they don’t provide it, that’s a red flag—file a formal request.
• If the EIR is too technical: Look for the section titled “Water Supply Assessment” or “Utilities.” You can also ask a local environmental group or university for help interpreting it.
• If the facility is already built and you have concerns: Ask for the facility’s ongoing water use reports, which are often submitted to the local utility annually. You can also ask the utility to track and disclose consumption.
• If you suspect the facility is violating its permit: Contact your state’s environmental protection agency or the local water board. They can investigate and take enforcement action.

Frequently Asked Questions

Q: How much water does a typical data center use?
A: It varies widely. A small facility might use 10,000 gallons per day, while a large hyperscale data center can use 1-5 million gallons per day, depending on cooling system and climate.

Q: Do data centers use drinking-quality water?
A: Many do, because they connect to the municipal supply. However, some are built near wastewater treatment plants to use recycled water. Ask your local utility if the data center is on potable water.

Q: Can data centers operate without water?
A: Yes, with air-cooled systems, but they use more electricity. Some operators choose air cooling in water-stressed areas, but it’s less efficient in hot climates.

Q: How does data center water use affect my water bill?
A: If the data center is a large customer, it may increase demand and potentially lead to higher water rates or infrastructure costs, but it’s not automatic. Ask your utility about rate structures.

Q: What is WUE?
A: Water Usage Effectiveness is a metric that measures how many liters of water are used per kilowatt-hour of IT energy. Lower is better. It helps compare efficiency across facilities.

Q: Can I find out how much water a specific data center uses?
A: Yes, often through public records requests or sustainability reports if the company publishes them. Some operators disclose water use voluntarily.

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