Bring the water, tea and rock candy to the boil in a large saucepan. Let it steep for 24 hours, then put it through a sieve into another pot.
Add grain and lemon flavor and fill into bottles. (Makes approx. 2 - 3 bottles) If you can`t get a finished raspberry-blackberry tea mixture, take a 125g bag of each variety. Also very tasty mixed with sparkling wine.