 Why does Joseph lie about the water supply?
What's fair is fair, and you have put a different complexion on what seemed at first to be an unconscionable interjection of a middleman between Nature and man's thirst." "On account of the quantity, I'm able to quote a bargain price. Shucks, boys, it hurts me more to charge for water than it does for you to pay. "Just the same," Joe griped, "paying for water isn't something you can get used to in ten minutes." In the fragile forest, they soon came across a stream that sprang from the igneous soil and splashed into the small pond whose contents, according to the mayor, was theirs for the asking. They filled their buckets and hauled them to the ship, then returned for more.
 He wants people to believe they need to pay for it.
 There isn't a lot of water there, and he needs to be able to ration it out.  He wants people to believe they need to pay for it.  He wants to keep the fresh water for himself.  He thinks that people would prefer to buy filtered water.