Elderflower cordial

30 elderflower heads 1 litre water 1kg sugar 2 lemons 30g citric acid Shake any bugs off the flowerheads and place in a large pot. Boil the water with the sugar and citric acid until dissolved then cool slightly and pour over the elderflowers and lemon. Leave to infuse for 3-4 days in the fridge. Strain through a cheesecloth and decant into bottles.