In a large saucepan, add the water and sugar and whisk together to blend. Bring to a boil and cook until all the sugar is dissolve. Stir regularly so it does not burn.
Remove pan from heat and let it cool slightly.
Add lemon juice and lemon zest to the sugar syrup and stir to blend. Allow it to cool to room temperature.
Meanwhile, prepare a muffin tin. I like to use silicone cups placed on a baking sheet so that they are easy to pop out when frozen. If you don’t have silicone muffin cups, you can use a regular tin. You will need to run it under warm water to pop them out more easily.
Pour Homemade Lemonade Concentrate in prepared muffin cups. Place pan on flat shelf in freezer. Freeze until solid (at least 2 hours). When frozen, pop out concentrate and store in a labeled ziptop bag.
To prepare Homemade Lemonade from concentrate:
By the glass: add ¼ cup concentrate to 8-10 ounces of cold plain water
By the pitcher: add 1 cup concentrate to 32 ounces (4 cups) of cold plain water
Stir to blend.