To make a simple syrup: Combine water and sugar in a small saucepan. Bring it to a boil on high heat and then reduce heat to low. Simmer for about 5 minutes or until the sugar has completely dissolved.

Remove from heat, pour the simple syrup into a separate container and let it cool down to room temperature. Then, store it in the refrigerator to chill.

In the meantime, squeeze the lemons and pour the juice into a large pitcher through a sieve to catch any pulp or seeds. Add the chilled simple syrup and the rest of the water. Stir well and store in the refrigerator to chill before serving.