When I first got into homebrewing, I felt completely overwhelmed by the range of techniques and equipment. There were mash tuns, sparge arms, wort chillers, and three-tier systems that looked more like lab equipment than something you’d use for making beer at home. I loved the idea of crafting beer from grain rather than extract, but the traditional all-grain setup just didn’t seem practical for my tiny apartment kitchen. That’s when I stumbled upon a method called brew in a bag—or BIAB—and everything changed.
Figuring out how to brew in a bag opened the door for me to take full control of my beer recipes without investing in a garage full of gear. It was straightforward, inexpensive, and worked perfectly for my small space. In this article, I’ll walk you through the method from start to finish, using my own experience to highlight what works, what to expect, and how to get great results every time.
What Is Brew in a Bag?
The brew in a bag method simplifies the all-grain brewing process by using a single pot for both mashing and boiling. Instead of transferring wort from one vessel to another like in traditional systems, you mash your grains inside a large, heat-resistant mesh bag that sits in your brew kettle. After the mash is complete, you lift out the bag, let it drain, and then proceed directly to the boil in the same kettle.
What makes learning how to brew in a bag such a game-changer for many homebrewers—myself included—is how accessible it makes all-grain brewing. There’s no need for fancy plumbing or multiple kettles. With a few affordable tools and a bit of patience, you can brew excellent beer in any kitchen, basement, or backyard.
Equipment You Need for BIAB
Before my first BIAB brew day, I did a quick check of what I already had on hand and what I needed to purchase. I was pleasantly surprised to find that I only needed one or two additional items beyond my basic brewing setup.
A Large Brewing Kettle
Your kettle must be big enough to hold your entire water volume and your grain bill. For a 5-gallon batch, I recommend a kettle that holds at least 8 to 10 gallons. I use a 10-gallon stainless steel pot, which gives me room for vigorous boils without worrying about spills.
A Brew Bag
The brew bag is the star of the show. It’s a reusable mesh sack that fits inside your kettle and holds your crushed grain during the mash. The bag needs to be fine enough to contain the grain husks but porous enough to let liquid pass through. Some come with handy handles or drawstrings for easy lifting.
Heat Source and Thermometer
I typically brew outside with a propane burner, but an electric stovetop or induction burner can also work for smaller batches. You’ll also need a reliable thermometer to check your mash temperature, which is key to enzymatic conversion.
Extras
A sturdy spoon or mash paddle helps with stirring, while a pulley or hook can make lifting a heavy, saturated grain bag much easier. Don’t forget essentials like a fermenter, airlock, sanitizer, and cleaning tools.
Step-by-Step Process of Brewing in a Bag
Step 1: Heat Your Water
Start by heating your entire water volume for the batch. Since BIAB doesn’t require sparging, you’ll use all your brewing water upfront. For my 5-gallon brews, I usually begin with 6.5 to 7 gallons of water to account for grain absorption and boil-off.
I heat the water to just above my desired mash temperature—usually around 160°F—so that when I add the grains, the temperature settles around 152°F. That’s a sweet spot for most beer styles.
Step 2: Mash Your Grains
Once the water is ready, I line my kettle with the brew bag and carefully add the crushed grain, stirring to prevent clumping. This step reminds me of making a big batch of oatmeal. It smells amazing and starts to give that familiar malty aroma right away.
After the grains are mixed in, I check the temperature and adjust if needed. I then cover the kettle and wrap it with blankets or towels to hold the heat steady during the mash. I typically mash for about 60 minutes.
Step 3: Lift and Drain the Bag
When the mash is finished, I slowly lift the grain bag from the kettle. This part can be a bit tricky if you’re brewing a larger batch, so I rigged up a pulley in my garage to help lift and suspend the bag. I let it drain back into the kettle for several minutes, and I gently squeeze it to extract more wort—but not too hard, since over-squeezing can release tannins that affect flavor.
At this point, you have your wort ready for boiling, and you haven’t even dirtied another vessel.
Step 4: The Boil
With the grain removed, I bring the wort to a rolling boil. From here, the process is no different from traditional brewing. I add hops at various stages depending on the recipe and let it boil for around 60 minutes.
One of the things I love about BIAB is how smooth the transition is from mash to boil—it saves time and simplifies cleanup, which means more energy for creativity.
Step 5: Chill and Ferment
After boiling, I cool the wort quickly using an immersion chiller, which I place directly into the kettle. Once it’s cooled to yeast-pitching temperature, I siphon it into my sanitized fermenter, pitch the yeast, and seal it up.
Fermentation proceeds just like any other brew, and before long, you’re well on your way to enjoying a homemade beer that you crafted entirely from grain.
Why BIAB Works So Well for Homebrewers
From my personal experience, learning how to brew in a bag has removed many of the barriers that often keep people from trying all-grain brewing. It’s inexpensive, efficient, and accessible—even if you’re working in a small apartment kitchen or don’t have space for a full brewing rig.
One reason I stick with BIAB is that it lets me focus more on the creative side of recipe formulation. I’m not distracted by managing multiple vessels or worrying about transfer losses. That simplicity helps me dial in flavors, experiment with ingredients, and maintain a consistent process.
Tips for Brewing in a Bag Successfully
Know Your Water Volume
Since you’re mashing with your full water volume, you’ll need to plan carefully for grain absorption and evaporation. Most grains absorb about 0.1 gallons of water per pound, and your boil-off rate will depend on your kettle and heat source.
Insulate the Kettle
Maintaining mash temperature is crucial for proper starch conversion. I often wrap my kettle in a sleeping bag or heavy towels and avoid removing the lid unless absolutely necessary. If I see the temperature dip, I apply low heat while stirring constantly.
Monitor Efficiency
Your brewhouse efficiency might differ slightly from traditional sparge methods. I noticed a small drop in efficiency initially, but I adjusted my grain bill accordingly. Over time, I fine-tuned my process and hit consistent targets.
Clean-Up Is a Breeze
One of my favorite perks of BIAB is the easy cleanup. The grain stays contained in the bag, and all you have to do is dump it out, rinse the bag, and sanitize the kettle. It’s a faster and less messy process compared to traditional setups.
Final Thoughts
If you’ve been wondering how to brew in a bag and whether it’s worth trying, I can confidently say yes. This method has allowed me to explore full all-grain brewing without needing a garage full of equipment or a steep learning curve. The simplicity of the process makes it accessible, while the results speak for themselves—great beer, brewed on your terms.
Whether you’re an extract brewer looking to take the next step, or a veteran homebrewer seeking a streamlined setup, brewing in a bag is a method that combines quality with convenience. It’s a game-changer, and I honestly can’t imagine going back.
