In a heavy pan, stir together the sugar and 1/2 liter of water over medium heat until the sugar is completely dissolved. Do not let it boil. Wipe any sugar crystals off the edge of the pan with a damp household towel.
Now bring to the boil, reduce the heat and continue to cook for 1 minute. Let cool down.
Leave the lemon peel, lemon juice and the additional water together with the cooled syrup in a large jug for approx. 2 hours to settle. Then pour through a sieve and pour into clean bottles if necessary. Put something into the fridge.