2 "fruit" tea bags (or peppermint, chamomile, lemon ginger - whatever you like)
1/2 litre boiling water
1/2 litre cool water
Steep the two teabags in the boiling water for about 4 minutes. Pour into a jug with the cool water. Chop the lemon into wedges and pop in. Keep it in the fridge. It's best drunk within 24 hours.