Brush the lemons under hot water and remove the peel thinly with a peeler.
Put the peel in a saucepan with the sugar and citric acid and mix.
Bring the water to a boil and add it. Allow to cool together. Squeeze the lemons and add the juice.
Leave the mixture to infuse until the next day.
Then strain the solids, fill the lemonade into clean bottles and seal them.
To drink, dilute the lemonade with mineral water or water to taste.