BIAB (Water Volumes)

I tried my first 5 gallon BIAB, I ended with twice the amount of wort I was shooting for. I have a question, I’ll give my thought process that includes fixing what I may have done wrong…does this look right?

(I have an 11 gallon kettle and 17.5lbs of grain)

6.56gal (Mash @ 152* for 60mins)
-2.60gal (Grain Absorption)

3.96gal (Wort)
+2.79gal (Question about this amount…)

6.75gal (full volume)
-1.25gal (boil off)

5.5 gallons (final volume)

the 2.79gallons to bring my volume up question: do i…

  1. Dump it into the 3.96gal of wort, then get temp up to 170*, lower grains back in, hold for 10 minutes, discard grains


  1. heat it to some other temperature (if so what temp?) and pour over grains above the 3.96gal of wort?

Bonus: Should I be pressing/squeezing out the grains at any point?

I hope this helps illustrate my questions. I figure for this whole thing I’d need is a about 9.35 gallons of water.

I like this calculator.

I’ll run you through my process, for what it’s worth.

Using it, to get a full mash volume of 8.94 gallon.

I do a dunk sparge mash out, and aim for equal volumes for my mash and sparge.

8.94Gallons total minus 2.19G for absorbtion = 6.75

6.75/2 (half for mash half sparge) =3.38 + 2.19 for absorbtion = 5.57 Gallons for mash water, and 3.38 gallons for the dunk sparge mash out.

This site has handy calculators to find out what you need for your strike water temp and sparge water temp.

After a 1 hour mash I pull the grain bag out, and dunk it into the sparge water. Give it a good stir, pull it out and combine all the water into the boil pot. I like to squeeze the crap out the the grain bag in my sparge kettle to get every last drip of extract out of it I can. Then discard the grains.

Good luck

Your grain absorption seems high. I’ve found that BIAB grain absorption is far less than in my cooler MLT. I do full volume mash, no sparge BIAB. Here’s my process for the BIAB I did on Sunday:

Strike/mash: 8gal @ 162.5, adding 12lbs of grain brought temp to 155
1 hour mash @ 155
Mashout @170 for 10 minutes
Pulled grain bag, squeeze, resulting in 7.5gal wort (-0.5gal absorption)
Boiled 60 min for final volume of 6gal (-1.5gal boil off)

I suppose the thicker mash could cause the higher absorption, but not sure as I’ve always done full volume with no sparge.


If you add all the water to the kettle, you’re doing a no-sparge routine and you’ll lose some efficiency (versus a batch-sparge of the same recipe). The savings in time and effort are worth the small increase in grain cost (IMO) and you might also find that the resulting wort is maltier versus a sparged recipe.

Absolutely. Plus, with BIAB since you don’t have to worry about a stuck sparge you can do a finer crush, which boosts efficiency. I’ve actually never appreciated the rumored loss of efficiency. Case in point, with batch sparge in my cooler MLT my efficiency averages 72%, while my no-sparge BIAB efficiency averages 79%. The highest efficiency I ever managed with the MLT was 76%. On Sunday I my BIAB efficiency was 82%.

Sorry for all the stats, I’m a nerd.

Can I do a Mashout and Sparge with BIAB? Could I heat whatever volume of wort i have after pulling grains out first time, heat that up to 170* and then dip grains back in for 10 minutes…pull grains out then pour the heated water over the grains to get me up to volume as a ‘sparge’?

What would the temperature of the heated water for sparging need to be…170*, or should it be hotter than that?

Thanks for the help with this process, I enjoy doing this more than dumping a bunch of extract in water.

[quote=“ishredthecello”]Can I do a Mashout and Sparge with BIAB?[/quote]You can certainly do both. There’s no reason to do a mashout though, that’s only applicable to fly-sparging (it’s how you denature the enzymes and lock in the fermentability when you’re going to be slowly drawing off wort). Sparging can be done in a couple of ways - I think the easiest is to have a second container of hot water on the side, pull the grain bag(s) and put them in the fresh water, then stir the grain a bit, pull the bag(s) and combine the two worts. Or you can use a colander that fits on top of the kettle, pull the bag(s), place in the colander, and pour hot water through the grain into the kettle. Keep the temp under 170F to minimize the risk of tannin extraction (or treat the water to reduce the pH or use RO water for the sparge).

Another reason to do a sparge is to help extract more sugars out of your mash. The hotter water will dissolve sugars more easily. It will aslo be more fluid, so it will drain faster and more completely out of your bag.

[quote=“CliffordBrewing”]Sorry for all the stats, I’m a nerd.[/quote]Me too. I did the math at some point and assuming 100% conversion and full recovery of the wort, a batch-sparge’s max efficiency for a given grain weight and kettle volume is about 6-10% greater than an equivalent no-sparge (the efficiency gap widens as the grain increases). Given all the variables in an individual brewer’s process that can impact both conversion and recovery, it’s reasonable that a no-sparge routine could produce a higher efficiency than a batch.