In a small pot, combine 1 cup of water and 1½ cups of sugar. Heat over medium heat while stirring occasionally until the mixture comes to a gentle simmer. Continue heating for about 4-5 minutes until the sugar is fully dissolved and the syrup is clear. Once ready, remove it from the heat and let it cool for a few minutes.

In a large mixing bowl, pour the cooled simple syrup and add 1 cup of freshly squeezed lemon juice. Stir the mixture well to ensure the lemon juice and syrup are thoroughly combined.

Gradually stir in 6 cups of water into the lemon juice and syrup mixture. Continue mixing until everything is well incorporated. Taste and adjust its strength by adding more water if needed.

Fill a pitcher with ice to keep your homemade lemonade chilled. Pour the lemonade over the ice and garnish with lemon slices. Serve immediately.