To condense one gallon of water requires 2,368 watt hours of electrical energy. Where does that come from?
You could build thousands of tiny turbines, each hooked up to a hamster wheel, to power the dehydrators. If there aren’t enough hamsters, use the rats that are plentiful in every crumbling city.
Maybe we could take all the people displaced from the city and put them on huge treadmills connected to generators.