h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Another category altogether, and surprising that no researchers covered that previously for inclusion in this somewhat iffy compilation.

They can be home made, but for on a hot day when something quick is desperately needed to quaff a thirst, there are many commercially available cordials and concentrates, most fruit or flower based.

My favourite is a cordial from fresh ginger root. (Belvoir, but not sure if brand names are allowed here.) Simply add sparkling water, diluting to bottle instructions or thereabouts. Beats commercially available ginger beer or ale, most of which these days inexplicably contains sugar and a sweetener, usually saccharine. And we can do without that, thank you.