Place the water and barley into a medium saucepan; cover, set over high heat and bring to a boil. Once the barley comes to a boil, decrease the heat to low and simmer for 30 minutes. While the liquid is cooking, peel the lemons, being careful not to cut into the white pith. Juice the lemons and place the juice along with the peel into a 3-quart pitcher and set aside.
After 30 minutes, strain the barley water through a fine mesh strainer into the pitcher. Discard the barley. Add the honey and stir to combine. Refrigerate until chilled.
Recipe courtesy of Alton Brown, 2006