Whenever this comes up, I mostly get annnoyed of 2 very different mentions of 4$: > it can be made from just $4 worth of materials. > it would cost just $4 to

Whenever this comes up, I mostly get annnoyed of 2 very different mentions of 4$: > it can be made from just $4 worth of materials. > it would cost just $4 to build These are not the same thing. Also I lack context of the cost of other desalination techniques and life spans of each.