Cooling is not one thing.
Withdrawal, consumption, reuse, potable demand avoided and electricity-linked water answer different questions.
Primary sources ↓ · Limitations ↓
- Bright publication
- Source review
- Reading question
- Which water crossed which boundary during which period?
Name the flow
Withdrawal is water taken from a source. Consumption is the portion not returned to that source, often because it evaporates. Reuse is water used again after treatment. Potable demand avoided compares against drinking-quality water that otherwise would have been used. Electricity-linked water sits outside the facility boundary and depends on the power supply.
Sources: A Guide to Data Center Energy Efficiency Metrics · EPA Quincy water-reuse case study
A low number can hide a different boundary
Water usage effectiveness is commonly reported in liters per kilowatt-hour of IT energy. It is useful for comparing a defined onsite boundary, but it does not automatically include upstream electricity, identify the water source or describe seasonal scarcity. Quincy’s operating reuse system is instructive because EPA reports both potable demand avoided and canal make-up water.
Sources: A Guide to Data Center Energy Efficiency Metrics · EPA Quincy water-reuse case study
What this guide does not establish
- WUE values are sensitive to climate, load, technology and reporting boundary.
- Annual totals can hide summer stress.
- “Water positive” claims require a separate accounting method and local hydrology.
Primary sources
A Guide to Data Center Energy Efficiency Metrics ↗
Definitions for PUE and WUE and their measurement limits.
EPA Quincy water-reuse case study ↗
Operating water balance and financing terms.
Source-reviewed 2026-09-19. Source review means Bright compared this explanation with the linked records; it is not independent replication or expert peer review by Bright.