Squeeze fresh lemons until you have approximately 1.5 cups of lemon juice, ensuring that any seeds or pulp are discarded. Transfer the juice to a pitcher.
Add granulated sugar to the lemon juice and stir until it completely dissolves.
Pour water into the pitcher and stir everything together well. Taste and adjust the amount of sugar for your desired sweetness level if needed.
Serve over ice.
Notes
For the best flavor, use freshly squeezed lemon juice. If you're using bottled juice, use 100% lemon juice, not from concentrate, for the best flavor.
Adjust the amount of sugar to your taste by starting with a small amount and adding more until it's as sweet as you like.