When these systems are designed for low ambient humidity areas, they use a desiccant based first stage, where desiccant wheel or loop captures water from the low humidity air, and then is heated in a chamber to "regenerate" it and drive off the water into a 100% humidity chamber where the condensation can happen.

The applications of condensate water sources typically aren't in areas where desalination is the competing technology -- usually the competition is piping water in from far away via a utility system.