Because there is a highly nonlinear utility of water, where enough to drink and cook is essential for survival, enough to bathe and wash is essential for a dece

Because there is a highly nonlinear utility of water, where enough to drink and cook is essential for survival, enough to bathe and wash is essential for a decent life, and then... nothing. If milk was $200 a gallon you could simply not buy any and you'd be fine, which is not the case with water.