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Back to Basics: Brew in a Bag

Back to Basics: Brew in a Bag

By Greig McGill

“What have the Aussies ever done for us?”, he asked, in a manner vaguely reminiscent of a member of the People’s Front of Judea. Or was it the Judean People’s Front? I guess that doesn’t matter, but the answer is certainly Brew-in-a-Bag. Brew-in-a-Bag (BIAB) is a relatively modern technique of all-grain homebrewing. The method involves placing crushed grains (your grist) in a mesh bag, which is then contained in a kettle of hot water at the appropriate temperature for mashing, and left to steep for enough time to ensure conversion of starches to fermentable sugars. After the steeping process, the bag is lifted out of the kettle, drained of wort, and the wort is boiled, hopped, and fermented in the same way as other homebrewing methods.The exact origin of BIAB is difficult to trace definitively, but there is evidence to suggest that the technique was first developed and popularised in Australia in the early to mid 2000s (and yes, it feels weird writing “the early to mid 2000s” as someone born in 1975).

The earliest mentions of BIAB can be found in a series of 2006 posts on the Australian homebrewing forum AHB ( They collect and refine previously posted information, and there’s some mention of an “original” post from a user named "Lumpy5oh", in which they describe a method of brewing that involves placing crushed grains in a bag and steeping them in a kettle of water, which is then boiled and fermented. This method is essentially identical to the BIAB technique that is used today.

In addition to this, the Australian homebrewing scene was particularly active in the early 2000s, with a number of influential figures and organisations promoting all-grain brewing techniques. The popularity of BIAB is also reflected in the fact that it has become a well-established technique in the Australian brewing community and is frequently discussed in local brewing forums and publications.

While it is possible that BIAB may have been independently developed in other countries around the same time, the evidence suggests that Australia played a significant role in the origin and popularisation of this homebrewing technique. But despite that, it’s a pretty cool innovation. Perhaps we can co-opt it as a Kiwi thing the way they stole Crowded House?

The BIAB method is popular now as a simpler and more cost-effective alternative to traditional all-grain brewing techniques that require more equipment and space. The technique also allows for more flexibility in terms of batch size and is considered a great way for beginners to get started with all-grain brewing. Oh, and did I mention the reduction in clean up time? No need to painstakingly scoop out and rinse your mash tun. Just dump the contents of the bag into your compost!

Does it make great beer though? Oh, you bet.

For example, in the prestigious American Homebrewers Association (AHA) National Homebrew Competition, BIAB brewers have won multiple medals in various categories over the years. In the 2021 competition, for instance, a BIAB brewer won a gold medal in the Belgian Dubbel category, while another BIAB brewer won a silver medal in the Fruit Beer category.

Similarly, in the Australian Amateur Brewing Championships, which is one of the largest and most highly regarded homebrewing competitions in Australia, BIAB brewers have also won numerous awards. In the 2020 competition, for example, a BIAB brewer won the overall champion award for their beer in the Pale Ale category.

These examples demonstrate that there is nothing “less than” about BIAB, and it’s a great technique for making any style of beer without the need for a complex mashing and lautering setup.So what do you need to get started? Like any brewery, you’ll need a kettle to collect and boil your wort. You’ll also need a bag, which will sit inside this kettle and contain your grist. You will need to pay attention to the type of bag you use, as it will need to be a fine enough mesh to allow no grain particles through, while also being able to handle the hot temperatures associated with mashing. Bonus marks if it can handle boiling temperature, as this is a good way to clean it. You will also need the same fermentation setup as for any other brewing method - see my first back-to-basics article for some recommendations there.

A brewday will start like any other, with heating your water to strike temperature, and crushing your grains. With BIAB, it is common to skip the sparging step altogether, settling for a casual rinse with 75C water and “squeezing the bag” to extract as much of the wort as possible. As this can be less efficient than a full traditional sparge, you can take advantage of the major strength of BIAB - the impossibility of having a stuck sparge! You can mill your grains as fine as you like, or simply run them through your mill twice. This will allow for excellent efficiency.

It really is as easy as:

  1. Line your kettle with your grain bag. Pro-tip: use clips to secure the bag to the rim of the kettle.
  2. Fill your kettle with hot strike water.
  3. Pour in your crushed grist, stirring well to avoid dough-balls (not my childhood nickname, honest…)
  4. Close up and insulate your kettle/bag (now acting as a mash tun), opening and stirring occasionally throughout the mash of at least 30 minutes to an hour. You can do a conversion test if you like, but most modern grains should achieve full conversion from starch to fermentable sugars within 30 minutes.
  5. Lift the bag out of the kettle - it will be heavy, so I highly recommend a winch/pulley system. Many people use an oven tray or similar to rest the bag above the kettle. Let all the wort drip out of the bag. If you like, you can sparge by pouring 75C water through the bag, and squeezing the remaining liquid out of the bag. Wear sturdy gloves while doing this to avoid burns!
  6. Once all your wort is collected in your kettle, it’s just like any other brew! Boil, hop, cool, transfer, ferment, package, drink!

If you think you’d like to give this method a go, here’s a shopping list for you:

  1. Kettle - you likely already have one of these!
  2. Grain bag - polyester or nylon with a fine mesh.
  3. Some good strong clips or clamps to secure the bag to the kettle rim.
  4. Some insulation for the kettle to allow it to hold temperature during the mash (or you can use electric temperature control if you have it).
  5. A trusty stirring spoon!
  6. Recommended: a winch or pulley system to allow you to safely lift the grain bag out of the kettle without straining your back, and a rack to rest it on to allow easy draining back into the kettle for boiling.

Don’t forget to clean the bag thoroughly after use, as it will end up reeking of rotting grain otherwise! A good hose-out, and a boil in water is a good method of dealing with this. You can even put it through the washing machine!

Here’s hoping this has got you inspired to try out all-grain brewing using arguably the easiest method to get into the hobby. Perhaps you’re already an all-grain brewer who wants to simplify your brewday, or perhaps, like me, it’s just the idea of less clean-up that piques your interest! Whatever the case, give it a bash, and talk to the friendly team at if you have any other questions.