Not OP, but coffee is really high on water use, and can be a big cause of deforestation in some cases. So they're probably getting at this.
Apparently producing coffee beans for one large coffee uses 140kg of water. Ok, that sounds like a lot.
But also apparently producing one meal worth of chicken takes 700kg of water. Over 3000kg of water for beef. So I think, in comparison, coffee water use if negligible.