brew in a bag biab full volume mash

Are you looking to make the switch from extract to all grain homebrewing? Or are you an all-grain brewer looking to simplify your brew day? Brewing in a bag may be what you’re looking for.

Brew In A Bag (BIAB) is a simple, quick, and cost-effective method to brew amazing all-grain beer. Using very basic equipment, you can follow any homebrew recipe to make any style of beer you want. Single vessel, no-sparge, full-volume brewing in a bag is a fun and time-saving way to brew beer at home.

What Is Brew In A Bag?

Brew In A Bag is the most straightforward and affordable way to start brewing all-grain beer. You mash, lauter, and boil all in the same vessel! This is possible through the use of a bag that holds the grain during the mash.

If you are an extract brewer, you already have most of the equipment for BIAB. All you need is a kettle, a bag, and a heat source. 

Traditional homebrew set-ups are three vessels: a hot liquor tank, a kettle, and a mash tun. These types of systems make amazing beer and offer brewers a ton of flexibility. We love three-vessel systems and still use them. But what makes BIAB systems so interesting is their simplicity. 

BIAB saves space for brewers who brew in small places. And it saves time during the brew day as there is no sparging step. Plus, cleaning up is a breeze since you just empty your grain bag into the trash or compost. No more shoveling out heavy, messy grain from a mash tun.

This article will focus on the no-sparge, full-volume mash style of BIAB. You’ll see a lot of variations in different homebrewer’s BIAB processes. We give a run-down of our favorite method which gives amazing results for all types of beer styles.

Equipment

The three main pieces of equipment to start brewing in a bag are simple: a kettle, a bag, and a heat source.

Kettle

Almost any typical brew kettle can be used for BIAB. Check out our favorite kettles to help you figure out what’s best for you. 

To brew 5 gallons of beer, you should be looking at a 15 gallon brew kettle. For BIAB, you won’t be sparging. That means that you’ll be starting with a lot more volume of water in the kettle.

If you want to brew smaller batches, BIAB is still a great choice. Always be sure your kettle is at least 2.5 times the size of your final volume going into the fermenter. For bigger batches, be aware that the larger you go, the heavier the bag will be to remove. Even for 5 gallons, the grain bag can be 30-40lbs when lifting to drain.

One last piece of advice for the kettle: consider using a false bottom. A false bottom is a perforated metal sheet that is elevated above the floor of the kettle. This makes sure that the grain bag isn’t touching the kettle’s bottom and prevents scorching.

Bag (or Basket)

The bag is the most important part of BIAB brewing. Brewers have many different options when choosing the type of bag. We recommend buying a high quality, fine mesh nylon bag.

The fine mesh helps filter out the tiny bits of grain. This leaves a nice, clear wort. Vendors sell bags in typical sizes or you can order custom dimensions to match your kettle. Make sure it’s durable as you don’t want the bag ripping. You’ll be using and re-using the bag every brew. A good quality bag can last years!

The bag should not touch the bottom of the kettle. If you don’t have a false bottom, you can attach the bag with clamps to the brim of the kettle.

Another option is something called Brew In A Basket. It’s the same principle as a bag, but using a stainless steel basket instead. These baskets, made with fine stainless steel mesh, allow the wort to run through. One great thing about using a metal basket is that the bottom is elevated on feet from the floor of the kettle. 

Heat Source

Propane, electric stove, or induction burners are the most common ways to heat your BIAB kettle. This style of brewing is so flexible, you can brew in your kitchen, garage, back deck, or balcony.

Immersion heaters are not typically used in BIAB as the coils get in the way of the bag inside the kettle.

Ingredients

Making the switch to BIAB is very easy for all homebrewers. The ingredients are exactly the same as for any other all-grain batch. 

To illustrate, here’s a sample recipe that we can’t get enough of. Assume 70% brewhouse efficiency. After a few batches, you’ll nail down your exact efficiency. We like to perform a 30 minute boil for an even quicker and easier brew day!

American Bison Saison

We love this beer for its dry finish, fruity esters, and straight forward grain and hop bills. This Saison is super refreshing yet complex enough to impress your beer geek friends.

Final Volume:Original Gravity:Final Gravity:ABV:IBU:SRM:
5.5 Gallons1.0481.0045.8%204.31

Fermentables

Amount
PPG°LBill %
6 lbPilsner371.860%
4 lbMaris Otter Pale383.7540%
10 lbTotal   

Hops

AmountVarietyAAUseTimeIBUBill %
0.5 ozMosaic12.5Boil30 min1216.7%
0.5 ozMosaic12.5Boil15 min7816.7%
2 ozMosaic12.5Whirlpool15 min
66.7%

Mash Guidelines

Single infusion mash at 150F for a very fermentable wort. This will keep this Saison dry and refreshing.

Here are some estimated volumes for the BIAB process. Start with this and keep good notes to make any necessary adjustments for your next brew!


Gallons 
Total mash water you need7.61
Grain absorption losses-1.25
Starting boil volume6.36
Boil-off losses-0.75
Hops absorption losses-0.11
Volume going into the fermenter5.5

Yeast and Fermentation

  • Wyeast – French Saison 3711 (or your favorite saison strain!)
  • Ferment at 73F for 2 weeks

Keg or bottle condition to a slightly higher carbonation level than typical American ales. Aim for 3.0 Volumes of CO2 to give this beer a refreshing and lively mouthfeel.

Consider using a yeast starter to get the most out of your yeast!

Brew In A Bag Process

The BIAB process is very simple, fun, and quick. Compared to a typical three-vessel homebrew day, expect to save about 2 to 2.5 hours when you BIAB! 

There are some aspects to BIAB that you need to pay special attention to. Let’s take a look at the process from start to finish:

Planning

A successful brew day always starts with a great plan. Make sure your brew-space is clean and orderly. Weigh out all your grain, hops, and collect your entire volume of brewing water in your kettle. If you’re going with our recipe above, print it out and have it on hand. You can use it as a checklist.

Calculate your water using a BIAB homebrew calculator. You can find plenty of examples online but this one is our favorite.

At this point, you can start to heat your water to the strike temperature. 

Crush Your Grain

For BIAB, we recommend a very fine crush. There is no risk of a stuck sparge since this is a no-sparge method! Be sure your bag is fine enough mesh to filter all the small bits of grain. The finer your crush, the better your efficiency will be.

If you don’t have a mill, ask your homebrew supplier to double-mill your grain. This means that they put the grain through their mill two times.

Mashing

Once your water is at the strike temperature, put your bag in the kettle, and secure with clamps, if using. Start to add your crushed grain and stir to avoid any dough balls.

With a high quality, thick-walled, stainless steel kettle (check out our article), your mash temperature should hold steady without extra heating. If you have a false bottom (or use a Brew In A Basket), you have the option to apply heat to the kettle during the mash to maintain temperature.

Related: The Best Brew Kettle For Every Type Of Homebrewer

If you find that the mash temperature is dropping, you can wrap up the kettle. We have used blankets, sleeping bags, or Reflectix insulation wrap. If you choose to wrap your kettle, never turn on your heat source – safety first!

Most BIAB brewers use a single infusion mash. Keeping the mash at a single temperature, between 150-155F, for about an hour works for most styles

Removing The Bag

Once your mash is finished, it’s time to remove the grain bag from the sweet wort you’ve just made. This step is called lautering. Get yourself a pair of heat resistant gloves for this step – the bag can be hot!

Carefully, lift the bag and allow the sweet wort to drain. The grain will be fully saturated and the bag will be very heavy at this point. Once the bag is above the brim of the kettle, allow it to drain fully.

Tips for Draining the Bag

There are a few different ways to make sure to get all the sweet wort drained from the bag:

  • Use a large (and sturdy!) colander or grill rack to set the bag on and allow it to drain. You can set this directly on top of the kettle or on top of a bucket. Add back the remaining wort before the start of the boil.
  • Hang the bag from a hook above the kettle and allow it to drain. Make sure your bag is reinforced to not rip it.
  • You can rig up a pulley above the kettle to help lift the bag straight up and hold it while draining.
  • Gently squeeze the bag to extract as much wort as possible. 

After your wort has drained, simply empty the grain out into the trash or compost. Rinse the bag and hang dry. Once the bag has dried, any last bit of grain can be shaken off. It’s ready for the next use. Cleaning up is as easy as that!

Boiling

As soon as the bag is draining, you can start heating your boil. From here, boiling your wort is exactly the same as any other brewing method. Add your hops according to the recipe along with any finings, if desired.

Chilling

Like boiling, chilling your wort is done the same way as any other brew method. For the fastest results, use an immersion chiller or a plate chiller. If you don’t have a dedicated chiller, you can always make an ice bath. Fill a tub or a large sink with ice and water and plunge your kettle into the icy water to chill. 

Once the wort is chilled to pitching temperature (65-75F), transfer it to your fermenter and pitch your yeast!

Final Thoughts

Many experienced brewers choose to use BIAB for its simplicity, quickness, and consistency. You can make world-class beer using a simple single vessel system in about three hours – right in your kitchen or garage!

We hope we convinced you of the power of brewing in a bag. Please leave a comment if you’d like to know more or have any questions.

FAQ

Should I squeeze the bag?

There is a lot of conversation online about whether or not to squeeze the bag as it drains. Some people say that squeezing the bag releases tannins from the grains. This could cause harsh and bitter flavor in the finished beer.

We recommend lightly squeezing the bag and allowing it to drain fully. You don’t need to wring it out like a wet towel, but it will help your efficiency to gently squeeze out as much wort as you can. Just be sure to protect your hands with some heat-proof gloves.

What mash efficiency should I expect?

BIAB is usually slightly less efficient than a traditional three-vessel homebrewing system. No-sparge brewing doesn’t “rinse” the grains in the same way to extract every last bit of sugar.

Increase your efficiency by paying attention to grain crush and mash temperatures/volumes. You can easily get a brewhouse efficiency of 70% and higher with some practice.

Help! What do I do if I burn my bag?

Unless you have a false bottom or use a Brew In A Basket, never apply heat when the bag is in the kettle. You will burn the bag and destroy it (not to mention ruin your brew day). Always pay extra attention that the bag does not touch the bottom of the kettle. If you burn a hole in your BIAB bag, you’ll need to buy a new one. The good thing is that they aren’t expensive so you can get back to brewing in no time.

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