Using a spoon, scrape the peel off the ginger and chop into medium pieces.
Add the ginger peels, chopped ginger, and lemon zest into a pitcher with 2 cups of the water.
Place the pitcher in the refrigerator to chill for at least an hour.
Pour the lemon ginger mixture into a blender and blend until smooth. Strain through a fine strainer to remove pulp.
Add the lemon juice, sugar and remaining 4 cups of water and mix. Place in the fridge to chill; serve over ice, and garnish with lemon slice, and a spring of mint.