I have watered down kits at the barreling stage on several occasions that I felt were a bit strong without problems. (mainly as I am a scrooge and wanrted more beer to sup)
its not ideal but its either that or you will end up with a very strong brew
the main thing I am unsure on is how sensitive beer yeasts are to alcohol levels - whether the yeast will have consumed all the fermentables or were stopped for other reasons.
there may also be a risk of oxygenated water being added and spoiling the beer but if added carefully this should be ok. (would pre-boiling help?)
how does it taste? this may be one of those mistakes that ends up a benefit - could be some real rocket fuel
