Place the glass upright in the center of your pot.
Fill the pot with saltwater. The water level must be lower than the top of your glass.
Put the lid on the pot upside down. The lid's handle should be directly above the glass.
Bring the water slowly to a boil. Purified water vapor will form on the lid and trickle down the handle into the glass.
Continue boiling the saltwater until almost all of it has been evaporated and condensed.
Take the glass of water out of your pot. Leave the water to cool, and then drink it.