 Why does Joseph lie about the water supply?
Paying no attention to them, it was carrying a case of liquor in two hands, six siphons in two others, and a broom and dustpan in the remaining pair. Through thirst-cracked lips he rasped: "Water—quick!" Medical science is unanimous in proclaiming this magic medicine the sole panacea in the entire history of therapeutics." Our condenser broke down, and we've gone without water for five ghastly days." He came near starving and moved on to Titan. It's bitter as some kinds of sin before it's purified. Waddya think—I was chargin' feller critters for water just out of devilment? 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." "And chief of police, no doubt," said Harvey jocosely. "About seventy-five liters, if we go on half rations," he answered. "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. The planetoid man worked the pump while the mayor intently watched the crude level-gauge, crying "Stop!" when it registered the proper amount. Then Johnson rubbed his thumb on his index finger and wetted his lips expectantly. He asked: "But what are we to do about replenishing our battery fluid?
 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.