i dont doubt anyones suggestions and expertise, but its not like im adding in LME or anything. i guess i just find it hard to believe that adding a little bit of water (less than a gallon) would have such an impact on anything.
As I indicated in my previous post, I would guess that the outcome would not be as you desired, which doesn't mean that it won't work out okay for you. I have not done what you suggest so can't give any first hand experience. If you end up doing this I would surely appreciate feedback on how it worked out - the final product that is.
I think of it as a bad idea from the standpoint of mouthfeel and flavor. Some mouthfeel is created from the yeast interaction during fermentation, and adding water at this point will water down that mouthfeel. Additionally, a flavor profile is created from the same yeast interaction which may again be thinned out to result in a less flavorful product. I can't say with any certainty that these "aspects" would be less or equal to what it would have been had you started with the correct amount of water to begin with, but I would venture a guess that it will be different (better or worse, I don't know). There are a multitude of other factors that play into the final beer you create that could/will be affected by the addition of water after fermentation.
BUT, when it comes down to it, I guess no one can have a certain description of it's impact unless we experiment. With this in mind, I think if you're willing to be a guinea pig then by all means - just make it count. Perhaps bottle a portion of the batch as it is (1 gallon maybe), and then water down the remainder with the correct proportion of water and bottle. In 4-8 weeks give us a report on how they compare (if you don't mind) because I would be interested in the outcome whether it be good or bad.
My biggest concerns, as I mentioned previously, are infection from the water and oxidizing the beer. I think you could avoid both of these possibilities by using well boiled water (cooled afterwards, of course). The boiling should kill any nasties in the water and remove oxygen at the same time. I would start with 1.5x the water you think you need and boil for 20 minutes - the long boil time is to give a chance for most of the oxygen to escape and the extra amount is for evaporation. The last point I would pay attention to is how you introduce the boiled water, keep the splashing to an extreme minimum (again, trying to avoid oxidizing the beer).
If you end up doing this I'm very interested in your results. Keep us posted - if you will.
