Separate four water questions
A water assessment should distinguish the volume supplied to a site, the portion consumed rather than returned, the freshwater source displaced by alternatives, and water associated with electricity generation elsewhere. LBNL's 2024 report distinguishes direct and electricity-related consumption and defines consumption as withdrawn water removed from the immediate cycle through evaporation or another irreversible process. These quantities answer different questions and should not share one ambiguous water-use label.
Build separate records for source, use, discharge and consumption. Identify potable supply, groundwater, surface water and alternative supplies without treating potable and freshwater as identical categories. Record where discharge goes and what conditions apply. A lower purchased-water bill may indicate substitution or a changed tariff; it does not by itself demonstrate lower total consumption or reduced pressure on a local watershed.
2024 United States Data Center Energy Usage Report — LBNL (external source) · Best Management Practice #14: Alternative Water Sources — DOE FEMP (external source)An annual total cannot size a water connection
FEMP's alternative-water implementation process begins with an end-use inventory and matching available supply to the intended application. Extend that inventory with demand over time. Annual liters describe total volume; liters per minute or another declared flow interval describe the supply rate the connection must support. A cooling system's hottest-day demand can matter even when its annual use is modest.
Prepare an hourly or appropriately resolved planning profile using site weather, equipment loading and cooling modes. Identify coincident peak demand, storage drawdown, refill timing and any supply interruption. Compare these requirements with a confirmed utility commitment and authorized withdrawal or discharge conditions. State the model's time resolution and uncertainty. Dividing an annual estimate by the hours in a year creates an average, not a verified peak or an approved water connection.
Alternative Water Projects: Implementation Steps — DOE FEMP (external source)A closed equipment loop leaves the final sink open
FEMP's direct-liquid-cooling schematic has an equipment loop transferring heat through a CDU to another circuit that reaches a cooling tower. The equipment coolant recirculates while the final stage still evaporates water. Closed loop therefore identifies one circuit boundary; it does not establish a zero-water facility. Conversely, a dry heat-rejection stage can reduce cooling-related onsite demand without eliminating domestic, maintenance or other water uses.
Annotate each circuit with fill, makeup, drain and treatment connections. Distinguish routine recirculation from losses, flushing and service events. Ask the supplier which boundary its water statement covers and whether that statement includes all seasonal modes. A credible public explanation identifies the path to the atmosphere or another heat sink and leaves the unverified volume unquantified.
Cooling Water Efficiency Opportunities for Federal Data Centers — DOE FEMP (external source)Freshwater substitution needs a supply and treatment plan
FEMP identifies alternatives such as reclaimed wastewater, captured condensate and harvested rainwater, with treatment chosen for the end use. Availability, storage, permits and ongoing maintenance remain important. An alternative supply can reduce freshwater withdrawal while the cooling process continues to consume water. Describe that outcome as freshwater substitution rather than claiming the facility stopped using water.
Compare supply timing with demand timing. Rainwater storage that is useful in one season may not cover a hot, dry operating period. Reclaimed supply needs a reliable service arrangement and compatible chemistry; condensate collection depends on the systems producing it. Include treatment electricity, reject streams, backflow protection and operator responsibilities in the evaluation. Do not assign the same source quality or uninterrupted availability to every site in a modular network.
Best Management Practice #14: Alternative Water Sources — DOE FEMP (external source) · Alternative Water Projects: Implementation Steps — DOE FEMP (external source)Lower onsite demand can move an impact upstream
LBNL's 2024 indirect-water analysis uses regional electricity mixes and acknowledges that facility-specific purchase agreements and behind-the-meter generation were not represented. It is an estimate with a declared boundary, not a measurement of an individual data center's supplier. FEMP also documents energy used to move and treat water. The electricity-water relationship therefore extends beyond a cooling-tower meter.
When comparing a dry and a wet alternative, keep modeled site water and cooling electricity side by side. If estimating upstream water, identify the generation dataset, geography, time period and accounting method. Do not multiply a national average by a proposed site's demand and present the result as observed consumption. Distinguish annual attribution from the consequence of changing demand in a particular hour, and disclose missing supply-chain water rather than silently treating it as zero.
2024 United States Data Center Energy Usage Report — LBNL (external source) · Facility Water Cycle and Emissions Crosswalk — DOE FEMP (external source)Measure the water balance and investigate differences
FEMP recommends metering makeup and blowdown and checking those flows against the intended cooling-tower chemistry. A practical monitoring plan should reconcile supply meters, end-use meters and discharge records over the same period. Track leaks and overflow separately so avoidable losses do not disappear inside an unexplained remainder.
Record meter accuracy, interval, missing data and treatment changes. Distinguish a metered withdrawal from an estimated evaporative loss; do not subtract a discharge estimate from a measured supply volume without stating the uncertainty. Investigate a changing balance alongside weather, load and operating mode. For a distributed fleet, retain site records before aggregation so a small portfolio average cannot conceal a stressed location or an unresolved local supply requirement.
Facility Water Cycle and Emissions Crosswalk — DOE FEMP (external source) · Best Management Practice #10: Cooling Tower Management — DOE FEMP (external source)Publish a bounded claim that can be checked
A useful future report would identify the site, operating period, source volumes, consumptive estimate, freshwater share, peak withdrawal interval and electricity-related assessment. It would include total demand as well as intensity and distinguish actual operation from design calculations. Attach the method and explain changes in equipment, occupancy or climate that affect comparisons.
For Aguasto, the present commitment is an evaluation and measurement discipline. No operating water outcome is established. Appropriate language describes which cooling and supply alternatives are being assessed, the inputs still required, and the evidence needed before a result can be reported. Water-neutral, zero-water or competitor-superiority claims need their own substantiated boundaries and evidence; an enclosure format or a recirculating loop cannot establish them.
2024 United States Data Center Energy Usage Report — LBNL (external source) · Alternative Water Projects: Implementation Steps — DOE FEMP (external source)Sources & verification
The register preserves each source's publication and verification date. Manufacturer claims and documentation are attributed; Aguasto has not run the cited products in production.
- 2024 United States Data Center Energy Usage Report — LBNL ↗
Historical estimates and 2028 scenarios; Direct and electricity-related water boundaries; Regional indirect-water methodology limitations. Publication: 2024-12-19. Verified: 2026-10-13.
- Best Management Practice #14: Alternative Water Sources — DOE FEMP ↗
Alternative water sources and cooling-tower makeup; Treatment, permits, storage and maintenance; Freshwater substitution differs from eliminated use. Publication: date not stated in the reviewed source. Verified: 2026-10-13.
- Alternative Water Projects: Implementation Steps — DOE FEMP ↗
Inventory water end uses; Match supply and treatment to applications; Size and maintain alternative water systems. Publication: date not stated in the reviewed source. Verified: 2026-10-13.
- Cooling Water Efficiency Opportunities for Federal Data Centers — DOE FEMP ↗
Closed equipment loop can reject to an evaporative tower; Annual site WUE definition; Treatment can add electricity and maintenance. Publication: 2019-01-09. Verified: 2026-10-13.
- Facility Water Cycle and Emissions Crosswalk — DOE FEMP ↗
Water supply, distribution and treatment use energy; Illustrative energy-water factors require local context. Publication: date not stated in the reviewed source. Verified: 2026-10-13.
- Best Management Practice #10: Cooling Tower Management — DOE FEMP ↗
Evaporation, drift, blowdown and leaks; Water chemistry limits concentration cycles; Makeup and blowdown metering. Publication: date not stated in the reviewed source. Verified: 2026-10-13.