Merely place a bottle of frozen grey water into a container. Allow the water inside to melt. Water will be formed from the condensation on the outside of the bottle.
DIY Water from air Turtle edition.
Power consumption: 1 pc fan, plus already running freezer to freeze salt water inside Coke bottles. The fan must force air into the container.
Sidekick Condensation deliver 500 ml in 11 hours.