A necessity is not something you "need," because otherwise you'll "die." In economics, "necessity" has a technical meaning.
Consider that the word "need" applies to means to an end only: you need X in order to achieve Y. But you want Y, period.
I need to tighten a few screws in the computer so that the fan stops vibrating. (Update. Nope, had to RMA the stupid fan.) But I want the piece and quiet once the fan operates silently. Even the latter can be thought of as a means to the most general of all ends: happiness.
Since "need" regards causality and has a technological not economic sense, this term should be purged from economics altogether. There are no consumer needs, only consumer wants.
Economic necessity then is something a lot of people have chosen to consume on a regular basis and to replenish the supply of as soon as they run out. Pomegranate juice is a necessity, as far as I am concerned, if I decide I always want have a bottle of it in the fridge.