Does ChatGPT use a bottle of water for every email it writes?
The claim: “ChatGPT drinks a bottle of water for every email it writes.”
Nobody has published it for today’s models. The best-known study (Li et al., UC Riverside) estimated GPT-3 used a 500 ml bottle for every 10 to 50 medium-length answers: 10 to 50 ml each. Company figures are far lower: OpenAI says about 0.32 ml per average question and Google 0.26 ml per median prompt, and neither says clearly whether it counts water used at power plants. A newer figure for an AI-written email also circulates, but Hum couldn’t read it on its page, so it isn’t used.
The bigger pictureWater is felt locally. In a recent year, US data centres used about 17 billion gallons on site, and about 211 billion more through the power plants that supplied them (Berkeley Lab estimates).
- 10 to 50 ml the study’s estimate per answer, GPT-3
- 500 ml what the claim says: a whole bottle
Why the claim misleads
The study measured an older model and spread one bottle over 10 to 50 answers. The retold version drops both.
What nobody knows yet
- No independent per-question water figure exists for current ChatGPT models.
- The companies don’t say clearly whether they count water used at power plants.
- The newer email figure is in a news article Hum couldn’t open.
Sources (5)
- Li, Yang, Islam, Ren (UC Riverside), Making AI Less Thirsty (GPT-3) Estimated
“GPT-3 needs to “drink” (i.e., consume) a 500ml bottle of water for roughly 10 – 50 medium-length responses”
Quote checked on the page, 18 Oct 2026 - OpenAI (Sam Altman) Company says so
“It also uses about 0.000085 gallons of water; roughly one fifteenth of a teaspoon.”
Quote checked on the page, 18 Oct 2026 - Google Cloud Company says so
“consumes 0.26 milliliters (or about five drops) of water”
Quote checked on the page, 18 Oct 2026 - The Conversation (citing Lawrence Berkeley National Laboratory, 2024) Estimated
“U.S. data centers consumed 17 billion gallons”
Quote checked on the page, 18 Oct 2026 - The Conversation (citing Lawrence Berkeley National Laboratory, 2024) Estimated
“an additional 211 billion gallons (800 billion liters) of water indirectly through the electricity that powers them”
Quote checked on the page, 18 Oct 2026
Hum’s sums
- 500 ml ÷ 50 answers = 10 ml
- 500 ml ÷ 10 answers = 50 ml
- 0.000085 gallons × 3,785 ml ≈ 0.32 ml
Cite this
Li, Yang, Islam, Ren (UC Riverside), Making AI Less Thirsty (GPT-3), as quoted in Hum, “Does ChatGPT use a bottle of water for every email it writes?”, https://humearth.org/q/bottle-of-water (quote checked 18 Oct 2026).
Cite the original source first; Hum is where you found it.
What do Wh, kWh and TWh mean?
Wh is a watt-hour: a 1-watt light left on for an hour. 1 kWh = 1,000 Wh, and 1 TWh = 1 billion kWh. Hum compares each number with something everyday so you don’t need the units.
Send this answer
“A bottle of water per ChatGPT email”: the study behind it said one 500 ml bottle per 10 to 50 answers, for GPT-3. For today’s models, nobody has published it.