[pairodice]

"So an algebraic expression could be crafted to calculate how high the mineral content of the tank water would rise if one knew how much water was used for other than drinking"
You're just trying to make my head hurt aren't you?  lol  
Where does this 'waste water' go?  How much is produced?  Would an RO system not work for boon docking because of this?  
Thanks for the input, I do appreciate it!