Not enough water added for top off

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New Member
Jan 17, 2008
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Ooops! Rookie move.

Did my 1st brew yesterday; partial boil Canadian draft using only malt extract & nottingham dry yeast. Fermentation seems to be chugging along nicely today.

However, I forgot to do 2 things before pitching the yeast.

1. I forgot to mark where the 5 gallons is on my 6.5 gallon carboy
2. I forgot to take an OG reading

I boiled 3 gallons of water, let it cool, & poured it into the primary then did a 2.5 gallon boil, added & mixed it in really good. I think the process of boiling all this water ended up in something less than 5 gallons total in my primary.

The batch liquid level is about 11 inches from the bottom of my standard 6.5 gallon carboy. It seems there is quite a bit of headroom in the bottle. If I had to guess, I'd say it might be more like 4 gallons.

Here are my rookie questions:

1. Should I add more pre-boiled water at this stage? (18-20 hrs after pitching the yeast) If so, how much?
2. My fermentation is doing fine, should I bother opening it up to take a gravity reading?
3. How will not enough water affect the batch? Will I end up with an extremely high level of alcohol? If so, can anything be done to offset that? The recipe said to expect about 4.9% ABV for a 5 gallon batch.

Any help greatly appreciated.
1. At this point, I'd leave it alone. From the sound of it, you're close enough.

2. Again, leave it. A gravity reading now will not tell you where you started.

3. If you actually are short on water, it will be higher in alcohol and flavor than you anticipated. It's an open question as to how much, though, since you don't know the volume. Before you rack or bottle, mark the level. After you rack or bottle, see how much water it takes to reach that mark. That way, you'll have some idea where you are (and, in the meantime, mark your volumes on the fermenter).

Your beer will end up fine. Don't sweat the minor mistakes you made, and learn from them for next time.

What I do when I get a new carboy is pour 1 gallon at a time into it and mark it with a paint marker (that I did not steal from work - I swear). This way I know exactally where I'm at at all times (i.e. I'll know how much was lost through the blowoff tube, or about how much funk is at the bottom)