barley water

noun2

1. •
   (UK) A soft drink made by boiling pearl barley with water, and adding flavouring and sugar.

   • Large quantities of barley water were consumed constantly, but in the old days, a special boy was kept to run out for beer. — 1945
2. •
   (no longer used) A decoction of barley used as a nutritive and demulcent.