Detroit is currently selling water for $23/thousand cubic feet, or about .000321/gallon. That's filtered, treated, and distributed to a tap in every home.
What do you imagine a fair price would be for untreated, pump-it-yourself groundwater?
When you pay for residential water, you're not actually paying for the water. You're paying infrastructure costs, the cost of running the pumping station and repairing the pipes to your house.