Rinse 3/4 cup barley under cold water until water runs clear. Place barley in a 2qt saucepan, along with 6 cups water and the zest of several lemons. Bring to a boil, reduce heat, and simmer 10 minutes. Strain, removing barley (can be saved for soup or used in another dish). Add 1/2 cup honey, stir to dissolve. Stir in juice of 2 lemons. Let mixture cool to room temperature, then bottle and keep cool until serving.