Bebe I agree with Fiona, it must be the concentrated amount. I've just looked up this type of product on the Tesco website and they give similar infor for their own no added sugar orange squash.

I must admit I drink quite a lot of this, I put a little in my water bottle when I go to work, drink almost all the 500 ml then top it up once or twice a day, so that the rest has only a hint of the juice.