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BIAB vs three-vessel brewing: which all-grain setup fits you?

One pot and a bag, or a hot liquor tank, a mash tun and a kettle. Both make all-grain beer; they ask very different things of your garage.

Updated November 2026 · 6 min read

A three-vessel homebrew rig with kettles and burners set up outdoors on a patio
The Brew Bag for 50–60 Qt KettlesThe Brew Bag Pro-Series for 10 Gal Coolers and Larger KettlesCONIE Nylon Straining Brew Bag, 18 x 24 in.Concord Stainless Brew Kettle, Weldless Fittings, 10 galClawhammer Supply 10.5 Gal Electric BIAB System, 120VLearn To Brew 10 Gal Igloo Mash Tun with False Bottom
Photo: home_brewing, CC BY-SA 2.0, via Flickr
The short version
  • BIAB mashes all the water and grain in one kettle, then you lift the bag out. For 5 gal (19 L) you want a 10 gal kettle, a bag sized to it and a way to heat about 8 gal.
  • Three-vessel heats water in a hot liquor tank, mashes in a separate tun (often a 10 gal cooler) and sparges into the boil kettle. More gear and space, easier 10 gal batches.
  • Electric all-in-ones (Anvil, BrewZilla, Grainfather) are BIAB with a basket and a built-in heater.
  • Propane burners for either method belong outdoors only; electric is the indoor and garage option.

BIAB vs three-vessel is the classic all-grain decision. Brew in a bag (BIAB) puts the crushed grain in a fine mesh bag inside your boil kettle, mashes with the full volume of water, then lifts the bag and boils. A three-vessel system uses a hot liquor tank (HLT) for water, a mash tun to hold the grain bed and a separate boil kettle, with sparge water rinsed through the grain to collect the wort.

Both produce the same kind of all-grain wort. This page compares them on kettle size, water volume, gear, space, time and safety, with picks from the brands in our brewing systems hub. If you are still on extract, read extract vs all-grain first.

Brew in a bag (BIAB)

One kettle, one mesh bag, full-volume mash; least gear for all-grain

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vs

Three-vessel

Hot liquor tank, mash tun and boil kettle; sparging and bigger batches

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Picks from each side

Brew in a bag (BIAB)

Three-vessel

BIAB vs three-vessel side by side

BIABThree-vessel
Vessels1 kettle + bagHLT + mash tun + boil kettle
Kettle for 5 gal10 gal recommended (full volume)8–10 gal boil kettle, plus tun and HLT
Mash thicknessThin (all the water)Thicker, then sparge
Sparging~ Optional dunk or pour-over✓ Fly or batch sparge
10 gal batches~ Needs 15–20 gal kettle and a hoist✓ Scales well
Footprint✓ Small✗ Large, often a stand
Pumps✗ Not needed~ Optional, common on bigger rigs
Cleanup✓ One kettle, rinse the bag✗ Three vessels and hoses
Heat sourceElectric all-in-one, electric BIAB kettle, or outdoor burnerUsually outdoor burners or 240V electric

Source: Palmer, How to Brew (mashing and lautering chapters)

How big a kettle do you need for BIAB?

Because BIAB holds all the brewing water plus the grain at once, kettle size is the limit. A worked example for a 5-gallon batch with 10 lb of grain, using typical figures (pre-boil of about 6.5 gal, grain absorption near 0.12 gal per lb, grain displacement near 0.08 gal per lb):

Volume in each vessel during the mash

5 gal batch, 10 lb grain; gallons (estimates)

BIAB kettle: 8.5 gal8.5 galBIAB kettle3-vessel mash tun: 4.6 gal4.6 gal3-vessel mash tun3-vessel boil kettle: 6.5 gal6.5 gal3-vessel boil kettle
Source: Estimate from typical absorption and mash-ratio figures in Palmer, How to Brew
7.7 galTotal water for this example (pre-boil + grain absorption)
3.75 galMash water at 1.5 qt/lb in a three-vessel tun
10 galKettle size that gives BIAB boil-over room

So an 8-gallon kettle is tight for a full-volume 5-gallon BIAB, and a 10-gallon kettle such as the Concord 40 qt (B01M6DIKBI) gives headroom. In three-vessel brewing the mash tun only holds the thicker mash, which is why a 10-gallon round cooler handles 5- and 10-gallon batches. Plug your own grain bill into the strike water calculator and the boil-off calculator.

What a BIAB setup needs

  • A bag that fits the kettle. The Brew Bag from Wilser is sized per kettle (50–60 qt, or 10 gal coolers and larger kettles) with poly straps; CONIE and Boao sell generic fine-mesh bags. Measure your kettle's diameter and height first.
  • A 10 gal kettle or an electric BIAB kettle. The Clawhammer Supply 10.5 gal 120V system is an electric BIAB kettle; all-in-ones replace the bag with a basket.
  • A way to lift and drain the bag. A wet 10 lb grain bill weighs much more than dry grain. Use a pulley, a hook or a rack, and wear heat-resistant gloves.
  • A chiller. See immersion vs plate chillers.
A mesh brew-in-a-bag liner hanging inside a kettle on a home stove
A kettle and a bag.Photo: Plutor, CC BY 2.0, via Flickr

What a three-vessel setup needs

  • A mash tun. A converted cooler with a false bottom and valve is the common home choice: the Learn To Brew and Quick Fit 10 gal Igloo tuns, or Northern Brewer's 12 gal all-grain starter kit.
  • A hot liquor tank. Any second kettle that holds your sparge water, ideally with a valve and thermometer.
  • A boil kettle of 8–15 gal. The Spike 15 gal kettle and the Concord 15 gal kettle suit 10 gal batches.
  • A sparge arm and, often, a pump. The Eagle sparge arm spreads water over the grain bed; a Chugger or MKII-style magnetic drive pump moves hot liquid without lifting full kettles.
  • Heat for two vessels. Usually two outdoor propane burners, or 240V electric elements installed by a licensed electrician.
A rotating sparge arm spraying water over the grain bed in a mash tun
Three-vessel systems sparge the grain bed.Photo: Unknown author, CC BY-SA 1.0, via Wikimedia Commons

Efficiency, clarity and control

Three-vessel brewers sparge, which rinses more sugar from the grain and usually reaches a higher mash efficiency with a standard crush. BIAB brewers compensate with a finer crush (the bag stops a stuck lauter) or by squeezing or dunk-sparging the bag. Either way, take a pre-boil gravity reading and adjust: a hydrometer or refractometer works here (see hydrometer vs refractometer).

Control over mash temperature is similar. A three-vessel cooler tun holds heat passively; BIAB in a kettle loses heat unless you wrap it or apply gentle heat while stirring. Electric all-in-ones solve this with a controller, which is why many BIAB brewers end up there.

Safety for both setups

Both methods move hot, heavy liquid. A full 10-gallon kettle holds far more weight than you can safely lift, so drain with a valve or a pump rather than pouring. In a garage, choose electric; propane is for open air away from the house.

Propane burners: outdoors onlyRun jet burners in open air, away from the house. CPSC says to keep fryer-style propane burners out of the garage, off the deck and away from the house; a garage, porch or carport with the door open is still not outdoors. Burning propane makes carbon monoxide. Leak-check fittings with soapy water and never leave a boil unattended.Source: CPSC holiday cooking safety
Electric brewing: GFCI and a licensed electricianPlug 120V and 240V systems only into a GFCI-protected circuit of the type the manual calls for, with no extension cords. A 1600 W system on 120V draws about 13.3 A (W ÷ V), close to a 15 A circuit’s limit. Have a licensed electrician install any new circuit, 120V or 240V.Source: Anvil Foundry manual (GFCI protection for 240V hookups); W ÷ V arithmetic

Who should choose which

Pick by situation

SituationBIABThree-vessel
First all-grain batch✓~
Small garage or apartment✓ Electric BIAB indoors✗
Regular 10 gal batches~ Heavy bag✓
Already own a cooler and two kettles~✓
Want the shortest cleanup✓✗
Want to learn fly sparging✗✓

Choose BIAB if you want all-grain with the least gear, a small footprint and 5-gallon batches. Choose three-vessel if you brew 10 gallons often, have outdoor space or a 240V setup, and enjoy the process. The going all-grain page lists the mill, chiller and water gear for both.

Mistakes to avoid

  1. Undersized BIAB kettle. An 8 gal pot filled with 8.5 gal of mash overflows; size up or brew smaller batches.
  2. A bag resting on the burner-heated kettle bottom. Mesh can scorch. Use a false bottom, rack or basket when you apply heat.
  3. Lifting a full kettle or a wet bag without a plan. Use a pulley and a valve; never carry hot wort.
  4. Running burners in the garage. Outdoors only, with the door open or not.
  5. Sparging too hot. Keep sparge water near 168°F (76°C) per Palmer to avoid extracting tannins.
  6. Ignoring water chemistry. Mash pH affects efficiency for both; see the water chemistry calculator.
Verdict

BIAB is the simplest way into all-grain: one 10-gallon kettle, a well-fitted bag and a chiller make a 5-gallon batch, and it works indoors with electric heat. Three-vessel is worth its space and cost if you brew 10-gallon batches or want to sparge. Electric all-in-ones sit between the two.

How we chose

We compared the two methods using Palmer's How to Brew mashing and lautering chapters, the listing data for the bags, kettles, tuns and pumps shown, and CPSC propane guidance. The volume chart is a worked estimate from typical figures, not a measurement.

Strike water calculatorStrike water temperature and volume for your mash with Palmer's infusion equation, plus step infusions and…Brewing water chemistry calculatorBrewing water salt calculator: gypsum, calcium chloride, Epsom, baking soda, salt and chalk to ppm, SO4:Cl…Dilution and boil-off calculatorDilute wort to a target gravity, and work out pre-boil volume from your boil-off rate, boil time and losses,…

Questions

BIAB vs three-vessel: which makes better beer?
Neither by default. Both produce all-grain wort; three-vessel usually gets higher efficiency through sparging, and BIAB makes up for it with a finer crush. Fermentation control and sanitation matter more for the final beer.
What size kettle do I need for 5 gallon BIAB?
A 10-gallon kettle is the comfortable size for a full-volume 5-gallon BIAB, because it holds about 8.5 gallons of water and grain in a typical 10 lb batch. An 8-gallon kettle works for smaller grain bills or with a sparge.
Do I need to sparge with BIAB?
No. Full-volume BIAB skips the sparge. Some brewers dunk the bag in a second pot of hot water or pour water over it to rinse out a little more sugar.
Can I do three-vessel brewing with a cooler?
Yes. A round 10-gallon cooler with a false bottom and valve is the classic home mash tun; it holds temperature well and handles 5- and 10-gallon batches.
Can I brew BIAB on a stove?
Small BIAB batches of 1–2.5 gallons fit many kitchen stoves. Full 5-gallon BIAB is usually too much for a stove; use an electric BIAB kettle or all-in-one, or a propane burner outdoors.
Is an electric all-in-one the same as BIAB?
Close: an all-in-one uses a rigid basket instead of a bag and adds a heater, controller and often a pump. See Anvil Foundry vs BrewZilla.

Sources

  1. John Palmer, How to Brew (online edition)
  2. American Homebrewers Association: How to brew
  3. CPSC: holiday cooking safety (outdoor-only propane fryers)
  4. Craft Beer & Brewing: Homebrew safety