When a jug with this bright, tasty and rather concentrated drink appears on your table, it becomes joyful, like in childhood.
Wash the lemons with a brush. Remove the zest from 3 lemons. Squeeze juice from all lemons. Pour bottled water into a large saucepan, bring to a boil and remove from heat.
Put the zest, juice and sugar in a saucepan with boiling water. Refrigerate for 6 hours. Strain, pour into a pitcher of ice, add lemon slices or mint sprigs.