Want vs Need

Here's an item that might help us change the way we think:

Do you know when is enough is enough? » Coolest Gadgets

"More or less every single day we hear from some one who is stating that we need to save water or cut down on waste, but how on earth are we supposed to know exactly how much water we need to survive? Well the people, who brought us seats made out of recycled egg cartons, think that they have come up with a very useful and practical way to answer that question."