Add water to increase volume post fermentation ?

[Tanglefoot]

After brewing my latest single hop American pale ale I realised I mistakenly added + 500gm extra pale Maris Otter resulting in an OG of 1.064 rather than planned 1.052. The volume was also short, 13.68L (3 gallons) rather than predicted 15L.

Is it ok to top up the missing 1.32L after fermentation has finished to bring the ABV down to nearer the original recipe ?
If so, is boiled water ok and is there a way to calculate new ABV ?

Recipe below, cheers !

https://share.brewfather.app/wPuUykbnLA0uCb

 

[StoutWolf]

I did similar with some wine I brewed last year. Second calculator here should help with the abv calculations etc.

brewersfriend.com

 

[Cheshire Cat]

Just add tap or bottled water no need to boil. Then gentle stir and recheck FG until you get the result you want.

 

[StJayJay]

One way to check would be to take the final gravity before dilution. Supposing the FG is as target, you’ll have about 7%abv. In 13.68 l, that is about 960mls of ethanol. If you top up with water to 15 l, 960ml is 6.4%.
If you want to get down to 5.5%, you’ll need to top up about 17.5 l.
The calculation steps for those would be:
-measure FG of your beer as is and plug in to abv calculator for %
- divide the abv (%) by 100
-multiply that figure by 13680
-result will be approximate volume of alcohol in ml.
To dilute to your target ABV, (assuming you want 5.5%.)
-multiply the alcohol volume (ml) by 100
-divide result by 5.5 (or your desired %)
-result will be the total volume in ml
-subtract 13680 from that figure and the figure will be your additional water volume .

 

[Tanglefoot]

Thanks fellas, I'll let it ferment out and wait to see what attenuation is like and how it tastes.
I don't usually brew anything over 6% ish but maybe I'll like it !

 

[Speccy]

The same thing happened with my last brew, so I topped it up with a couple of litres of tap water just before bottling.

That was a couple of weeks ago, and an early sample last weekend (I can never resist...) had an overpowering smoky taste, to the point of being undrinkable. A bit of Googling suggests this might be down to chlorine in the water, which I didn't bother to boil before adding. Hopefully the smokiness will mellow over time, but if it stays the way it is, the whole lot's going down the sink.

If I top up a brew again I'll either boil the water first (the recommendation seems to be a good 15 mins or so), or use bottled water.

 

[little_wings]

Seems like a 1 way trip to oxidising your beer.. I'd leave it personally.

 

[Covrich]

one way you could do it is to boil up a larger priming solution of say just over a litre with the sugar and then rack on to that. I would be a touch cautious now will topping it up too much as you may feel like you diluted the flavour you have