Methodology and Data Sources

§1 Direct Water Consumption (Scope 1)

Direct water consumption refers to water withdrawn and consumed on-site by the data center's cooling system. For evaporative cooling — the dominant method in hyperscale facilities — water is circulated through cooling towers where a portion evaporates to dissipate heat.

The water consumption rate (L/kWh) is determined by the cooling system type. The most widely cited figure is 1.8 liters per kWh of IT load for evaporative cooling, sourced from Lawrence Berkeley National Laboratory's 2021 assessment of data center water use.

Annual consumption is calculated as daily × 365. We assume continuous operation (8,760 hours/year), which is standard for hyperscale data centers. Actual utilization rates vary but are typically 85–95% for large facilities.

Acre-feet conversion: 1 acre-foot = 325,851 gallons.

§2 Community Impact Metrics

Community impact metrics translate raw consumption figures into terms meaningful to local policymakers and residents.

Household Equivalency

The 150 gallons per household per day figure comes from USGS estimates of average domestic water use (approximately 82 gallons per person per day × 1.83 persons per household, with some rounding). This is a national average; actual use varies regionally.

Share of Utility Capacity

System capacity (in million gallons per day, MGD) is the maximum daily production capacity of the water utility serving the jurisdiction. This metric shows the proportional demand a single facility places on local water infrastructure.

Annual Water Cost

Municipal water rates are sourced from each utility's published rate schedules. Data centers may negotiate industrial rates; the figures shown use the standard commercial/industrial rate tier as a baseline.

§3 Indirect Water Consumption (Scope 2)

Indirect or "Scope 2" water is the water consumed by power plants to generate the electricity used by the data center. Thermoelectric power generation is the largest category of water withdrawal in the United States (USGS Circular 1441), and a significant consumer of water.

Grid water intensity (gallons per kWh) varies by region and depends on the generation mix:

Regional Grid Water Intensity

We calculate a weighted average water intensity for each grid region based on its generation mix (from EIA Form 923) and the water intensity of each fuel type:

These weighted figures are based on 2023 EIA Form 923 data (the most recent complete reporting year) combined with NREL water intensity factors. The methodology follows the approach used by the WRI Aqueduct water risk framework.

§4 Electricity and Rate Impact

Local utility peak capacity is sourced from the relevant ISO/RTO (PJM, MISO, WECC) load data. This represents the peak demand served by the utility in the jurisdiction's service territory.

Residential Rate Impact

The estimated residential rate impact is a range based on historical precedent from large industrial loads entering utility service territories. The methodology considers:

• Transmission infrastructure — new substations, distribution upgrades, and interconnection costs recovered through rate base
• Generation adequacy — whether new generation capacity must be added to serve the incremental load
• Demand charges — whether the large customer receives preferential economic development rates that shift costs to residential ratepayers

The range shown ($X–$Y per household per month) reflects uncertainty in how regulators allocate costs. The low end assumes full cost recovery from the data center customer; the high end assumes significant socialized cost allocation. Sources: EIA state electricity rate data, utility rate case filings, and LBNL grid reliability studies.

§5 Cooling System Parameters

The evaporative cooling rate of 1.8 L/kWh represents a fleet average across surveyed hyperscale facilities. Individual facilities range from approximately 1.2 to 2.5 L/kWh depending on climate, wet-bulb temperature, cycles of concentration, and equipment efficiency. Arid climates (Arizona, Texas) tend toward the higher end of this range.

§6 Location-Specific Data

Water stress index: Sourced from WRI Aqueduct 4.0 (2023 baseline year). Scale: 0–1 Low, 1–2 Low-Medium, 2–3 Medium-High, 3–4 High, 4–5 Extremely High. Index values are at the HUC-8 basin level for the primary water source serving each jurisdiction.

Utility capacity: Maximum daily production capacity as reported in each utility's most recent annual report or Consumer Confidence Report (CCR). Actual average daily production is typically 50–70% of capacity.

Water rates: Standard commercial/industrial rate per 1,000 gallons from each utility's published rate schedule (as of Q1 2026). Data centers may negotiate separate rate agreements not reflected here.

§7 Limitations and Assumptions

• Continuous operation assumed. Calculations assume 24/7/365 operation at the specified IT load. In practice, utilization ramps up over months or years and averages 85–95% for mature facilities.
• Climate not modeled. Evaporative cooling efficiency varies significantly with climate. Wet-bulb temperature, humidity, and seasonal variation are not factored into the base rate. Arid climates may see 30–50% higher water use per kWh.
• Single-facility analysis. Community impact metrics measure one facility's impact. Cumulative impact from multiple data centers in the same jurisdiction may be significantly higher. The ICPRB March 2026 study found data centers collectively account for 9–12% of Potomac consumptive use during summer peak.
• Static grid mix. Indirect water calculations use current grid mix data. Facilities with dedicated PPAs, on-site generation, or renewable energy certificates may have different indirect water profiles.
• Rate impact uncertainty. Residential electricity rate impact carries high uncertainty and depends on regulatory decisions, utility negotiations, and cost allocation methodologies not publicly available during the permitting process.
• Reclaimed water not modeled. Some facilities use treated wastewater or reclaimed water. This reduces freshwater withdrawal but not total consumption. The tool does not currently differentiate between freshwater and reclaimed water sources.
• Not engineering analysis. This tool provides planning-level estimates for public information and policy discussion. It does not constitute engineering analysis, environmental impact assessment, or regulatory determination.

§8 Data Sources and References

• [1] Lawrence Berkeley National Laboratory. "United States Data Center Energy Usage Report." 2021. escholarship.org/uc/item/2f04q62m
• [2] World Resources Institute. "Aqueduct Water Risk Atlas 4.0." 2023. wri.org/applications/aqueduct/water-risk-atlas
• [3] U.S. Energy Information Administration. "Form EIA-923: Power Plant Operations Report." Annual. eia.gov/electricity/annual
• [4] U.S. Geological Survey. "Estimated Use of Water in the United States." Circular 1441, 2018. pubs.usgs.gov/circ/1441
• [5] National Renewable Energy Laboratory. "Consumptive Water Use for U.S. Power Production." NREL/TP-550-33905, 2003. nrel.gov/docs/fy04osti/33905.pdf
• [6] PJM Interconnection. "Market Data Dictionary and Load Reports." pjm.com/markets-and-operations
• [7] Interstate Commission on the Potomac River Basin. "Data Center Water Use and Potomac River Basin Impact." March 2026. icprb.org
• [8] WSSC Water. "2024 Annual Report and Water Quality Report." wsscwater.com/water-quality
• [9] Google. "2024 Environmental Report." sustainability.google
• [10] Microsoft. "2024 Environmental Sustainability Report." microsoft.com
• [11] Amazon Web Services. "Water Stewardship." sustainability.aboutamazon.com
• [12] U.S. EIA. "State Electricity Profiles." eia.gov/electricity/state

§9 About WaterMark

WaterMark is a data center water impact assessment tool developed by Standard Water Corp (SWCo). It provides transparent, source-cited estimates of water consumption and community impact for proposed and existing data center facilities.

The tool was built to address a critical information gap: communities facing data center proposals lack accessible, independent tools to evaluate water impact claims. Corporate sustainability disclosures exclude indirect water, environmental impact statements are often unavailable during early planning stages, and consulting assessments are typically funded by developers.

WaterMark is not affiliated with any data center developer, utility, or government agency. All calculations and data sources are publicly documented on this page.

Contact

For questions, corrections, data source updates, or partnership inquiries:

• Email: ravi@standardwater.co
• Web: liquidassets.cc

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