The easiest way to be sure you are adding the right amount of water is to weigh or measure the 960 g (four cups) of water, fill two ice cube trays and freeze them, and chill any remaining water that doesn't fit in the trays. (If you already have ice made or if you have an ice maker in your fridge, you can use 32 regular size ice cubes and then add additional water to taste at the end.)

Make the mint simple syrup. Combine the 480 g (two cups) of water, sugar, salt, and mint leaves in a small saucepan.

Stir the sugar mixture over medium heat until the sugar is fully dissolved. Then, bring the mixture to a boil while stirring occasionally. Remove the pan from the heat and let stand for ten minutes.

Add the lemon juice to a large pitcher that is big enough to hold ten cups.

Strain the mint simple syrup into the pitcher with the lemon juice.

Add the ice and chilled water to the pitcher and stir until the ice is dissolved.

Add additional cold water to taste if the lemonade is too strong. (Keep in mind that serving the lemonade over ice will also dilute it somewhat.) Your lemonade is ready to serve!