Wash lemons and peel off all the zest using a vegetable peeler; set peeled lemons aside. Add lemon zest to a bowl and cover with sugar; toss to combine. Cover and let sit for a minimum of 2 hours, or up to overnight.
Bring water to a boil in a pot over high heat; turn off heat and pour in lemon-sugar mixture. Stir and let sit until sugar is completely dissolved, about 5 minutes.
Pour through a mesh strainer back into the same bowl and discard the zest. Let cool to room temperature, 20-30 minutes.
Cut lemons in half and squeeze juice into the bowl. Pour lemonade into a serving pitcher; cover and chill thoroughly before serving over ice, at least 2 hours.
