BIAB Water Amount

How does one figure out the amount of water needed for a no sparge BIAB batch. I know that the idea is that you use the total amount of water you'd use if you were mashing, then sparging, but I'm working towards my first AG batch (which will also be BIAB), so I'm a little shaky on this step. Thanks!

Your final volume + whatever you boiloff is for a 60 or 90 minute boil. I usually boil off a gallon in an hour. So for me it would be 6 gallons, or 6.5 for a 90 minute. Approximately.

Don't you have to allow for absorption by the grain too?

Revvy said:

Your final volume + whatever you boiloff is for a 60 or 90 minute boil. I usually boil off a gallon in an hour. So for me it would be 6 gallons, or 6.5 for a 90 minute. Approximately.

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Plus what you'd lose to grain absorption, no?

Yeah, I forgot about that, but;

...Take into consideration that the water absorbed by the grain with this method is about HALF that of a typical all grain brew session that utilizes a MLT.

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And if you are squeezing the hell out of the bag after, you'll get a lot back.

Once you do it the first time, and you start with 6.5 to be conservative and have to top off after your boil, you'll know for next time what it will be.

On my BIAB batches I have found that I absorb .06 gal per pound of grain.

djt17 said:

On my BIAB batches I have found that I absorb .06 gal per pound of grain.

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bytemyfoot, use this ^ when you are figuring out your initial water, if you are wrong you can re-calculate your needs for next time.

I found a spreadsheet on the web to calculate this, called "Set-Up Volumes for New BIABrewers - A Ball Park Guide." Sorry, but I cannot find the link at the moment and I do not appear to be able to attach the file here.

Anyway, I converted it from metric to English units, and here is what I use on my BIAB brews. This has worked well for me thus far, but I will continue to refine it as I do more BIAB batches.

Basically, for 5 gal out of the fermenter and a 10.25 lb grain bill:
-I start with 9.26 gal
-Lose 0.77 gal to grain absorption (0.075/lb ) to 8.49 gal start of boil volume
-Lose 2.59 gal to evaporation on a 90 min boil (calculated as the surface area of the kettle times .00729 gal per sq in per hour) to 5.9 gal post boil volume
-Lose 0.5 gal to kettle trub and buffer to 5.4 gal into the fermentor (calculated as 0.1 gal times the finished brew volume)
-Lose 0.4 gal to fermenter trub to 5.0 gal finished brew volume (calculated as 0.08 gal times the finished brew volume)

MEASUREMENT Units Comment
Finished Brew Volume 5.00 gal How much beer you want to end up with.
Fermenter Trub* 0.40 gal Volume left in fermenter after kegging/bottling.
Volume into Fermenter 5.40 gal End of boil volume less kettle trub & buffer.
Kettle Trub & Buffer** 0.50 gal Grain & hop trub plus some breathing space!
End of Boil Volume - Batch Size 5.90 gal Use this figure as your software batch size.
Boil Length 90 min 90 minutes recommended.
Diameter of Kettle 17.375 cm The widest diameter of your kettle.
Evaporation Per Hour*** 1.73 gal Stays fairly constant regardless of batch size.
Evaporation for this Brew 2.59 gal Derived from boil length & evaporation per hr.
Start of Boil Volume 8.49 gal End of boil volume plus evap, for this brew.
Grain Bill 10.25 lbs Pounds of grain used in this brew.
Grain Absorption**** 0.77 gal How much liquid is retained in the spent grain.
Water Required is... 9.26 gal How much water you need for this brew.
Kettle Calibration Figure ***** 0.940 in/gal (Straight sided kettles only.)
Fill Your Kettle to... 8.701 in (Straight sided kettles only.)

Obviously it varies by your setup but I start with 30 quarts and wind up with 5.2ish gallons. Lose about a gallon to grain absorption (I estimate .1 gallons per pound of grain) Boil off a little more than a gallon in a 60 minute boil and I lose very little to trub/dead space based on my pick up tube location.

I don't squeeze the bag very much, I leave it hanging over a clean bucket next to the kettle and pour whats dripped out after about 30 min into the boil.