Mix the elderflower umbels, lemon wedges and sugar in a large bowl and add the water. Stir well and let the bowl (with lid) stand for 2-3 days. Stirring occasionally.
If a slight foam forms, pour off the liquid through a sieve and fill it into bottles (no plastic bottles, they cannot cope with the pressure). Close tightly and store in a cool place for another 10 days.
Then the champagne is ready. It keeps for about 2 months, but should definitely be stored in a cool place, but above all it should be drunk cool.