Can I add water after fermentation?

[brianpablo]

I have a fairly primitive cooling system so I can brew more than about 2.5 gallons if I want to keep it at any decent fermentation temperature. It occurred to me that I could make a beer of higher gravity and then water it back down to the strength I want when bottling. Has anyone done this sort of thing? I would obviously have to adjust the hope extraction to keep the bitterness steady, and potentially add some invert sugar ensure fermentability. Appreciate your thoughts.

 

[billl]

If you are talking more than a minor dilution, I can't think of many styles that would work well with. If you are talking something like 2.5 to 5 gallons, you wouldn't be able to brew anything over 50 IBU in the finished batch. You also aren't going to be able to scale flavor additions and aroma. Also, you are going to have a heck of a time fermenting a 1.140 batch to dilute to a 1.070 batch.

Anyway, there is a simple and cheap way to cool larger batches. Just search for swamp cooler.

 

[andrewmaixner]

It might be much easier (and less prone to make crappy beer) if you just change your cooling system instead. Would need a lot more information though.
I've fermented successful 5Gal lager batches with San Francisco lager yeast (a high temp lager strain) at 55-60F using just a cooler full of water to set the carboy in, and dropping in frozen 20oz soda bottles as needed to control temperature. I threw a winter jacket over it to help prevent the ambient air from warming it up much also. I actually put TWO 5Gal carboys in it at the same time, since the cooler was large enough, for a 10gal batch with only ice/water cooling.

 

[brianpablo]

OK, thanks for talking me out of that one. Swamp coolers don't work great in these temperatures, they really never get below 70 at their coolest. And they tend to piss of SWMBO since they involve running a fan for three days in a service area where we often leave the dog. I could also just do a 5 gallon batch split into 2 2.5 gallon carboys held in two different coolers (the 6.5 gallon carboy won't fit into either of my coolers). Or yeah, buy another cooler.

 

[Qhrumphf]

Other concerns already listed aside, another issue with diluting with water post-fermentation is dissolved oxygen in the water. If you want to do it, the ideal scenario is a water deaerator capable of reducing water to <50ppb dissolved oxygen (pros who brew concentrated and dilute do this, it's not really practical for a homebrewer to have). Boiling only brings it down to multiple parts per million, not lower end of parts per billion. Tasty McDole has a method that involves boiling, then transferring to a keg, force carbonating, and chilling, that would scrub out some additional oxygen with CO2, but unless you push it to the <50ppb level, you'll be reducing the shelf life and hastening oxidation. For a quick consumption beer, may not be an issue. But if it's something you intend to hold onto for a while, it could pose a problem.

Like these folks said, if you want to brew bigger batches changing the cooling setup is a much better option.