—per request
—on-site cooling
—off-site generation
What that volume of water looks like
Equivalents use 500 ml per bottle, 65 L for an eight-minute shower, 2 L of drinking water per person per day and 2,500,000 L for an Olympic pool. They are there for scale, not to imply the water is interchangeable — cooling water and drinking water are drawn from different systems and returned differently.
Same workload, different region
Cooling design and climate move the on-site half by more than an order of magnitude. The grid behind the plug moves the off-site half. Neither alone tells the story.
| Region / cooling | On-site | Off-site | Total / month | ml / request |
|---|
Reference WUE and grid water-intensity ranges from public disclosures; individual sites vary by season and methodology. Click a row's values into the fields above by editing them directly.
Energy is the input; water is one of the outputs
Every litre on this page starts as a kilowatt-hour, which is why the fastest way to cut a water footprint is to cut tokens rather than to argue about cooling. A shorter system prompt, a smaller model for the easy 80% of traffic, and a cache in front of repeated questions each remove energy before it is ever drawn. Price the same traffic in kilowatt-hours and CO₂e on the AI inference energy & carbon calculator, see what the tokens themselves cost on the LLM token cost calculator, model routing the cheap traffic away on the LLM cascade savings calculator, and check how much repeat traffic a cache would absorb with the semantic cache ROI calculator.
How this calculator works
The AI Water Footprint Calculator works forward from energy. Your requests per month multiplied by energy per request gives the IT load in kilowatt-hours; multiplying by PUE adds the cooling, power conversion and lighting overhead to get facility energy. That facility energy is then converted into water twice. On-site water is facility kilowatt-hours times WUE, the litres evaporated per kilowatt-hour in the building's cooling system. Off-site water is the same facility energy times the grid water intensity, the litres consumed per kilowatt-hour at the power stations that supplied it. Adding the two gives the all-in figure, and dividing by requests gives the millilitres-per-prompt number the headlines quote.
The input that moves the result most is energy per request, which varies by more than a hundredfold between a small model answering in a sentence and a reasoning model thinking for thousands of tokens — so the model-class preset is the first thing to get right. After that, region matters: free-cooled northern sites report WUE an order of magnitude below evaporatively cooled sites in hot dry climates, which is what the region table quantifies. Off-site water usually exceeds on-site water on a thermal-heavy grid, which is why reporting only one of them can make the same workload look either negligible or alarming. All values are reference estimates from public disclosures and vary by site, season and methodology.