Multininjaed, so probably repeating someone or other.
Ah.
You make grog by mixing water and alcohol?
It's not so much an attempt to extend alcohol by watering it down, but more in order to extend the water. Or at least disguise how foul the might be. The details depend very much on the navy concerned, though, and the point in history.
[quite]Swill sounds like something for desperate times. That could be...interesting, at least.[/quote]'Swill' is generally a mix, of some kind. 'Pig Swill' (or pigswill, or pigs' swill?) is a mix of scrap food/liquid, but bar-swill/whatever-the-spelling-you-prefer means
to me the sort of thing you get from dregs of the overspill tray underneath the taps. In a modern-day pub, they'd get
shot for serving the stuff. Back in the old days, no doubt it was served as cheap alternative, to those that wanted it/couldn't afford anything else. And I know for certain that it was in the ingredients of the war-time swill (along with whatever other foodstuffs fell below even war-time standards) fed to the pig often jointly looked after by a community. A small part of it. Drunk pigs were no fun to control.
Anyway, history lesson (or at least circumstances as I know of them) over.
DF-wise, I don't know how swill could be produced[1], but if it existed I would have imagined that it would prevent the alcohol-withdrawal symptoms, but still give bad thoughts approaching that of having to drink water.
Grog is easier to imagine. Eke's out the alcohol (similar effects to those just suggested, for slightly different reasons) when supplies are low.
As a new form of environmentally-flowing liquid, the arguments against that are already mentioned, but in standard liquid-carrying vessels (of the various kinds), well, maybe. But perhaps pick either swill
or grog.
[1] The only way I can think of is that barrels maybe have an odd number of units of alcohol in them, but dwarves drink an even number of units. The final unit at the bottom of the barrel can only be added to other barrel-remainders.