Finely grate the rind of the lemons, the yellow colored part only, avoiding any white pith. Reserve the zest. Slice off the ends of each lemon with a sharp paring knife, stand up on end, and cut the rest of the rind completely off the lemons. Discard the rind. Slice each peeled lemon into thin slices crosswise and reserve.

Place the barley and water together in a large saucepan or pot. Bring to a full boil, and then reduce heat to a slow simmer.

Add in the reserved finely grated lemon rind. Simmer, covered, for 45 minutes.

Remove from heat, and strain the liquid out into a heat proof mixing bowl, pressing on the solids to extract any liquid.

Add in the sugar to taste, honey, and the reserved sliced and peeled lemons. Stir until the sugar is completely dissolved.

Cool down the liquid until it comes to room temperature, then strain it the pearl barley water into a pitcher. Chill until cold.

Serve over ice.

Barley water will keep for about 5 days in the refrigerator. Stir well before serving.