Decanting a cask into a Bag-in-Box


I own a pub and it is tied – so can only get 9g casks of real ale.

We sell through enough to have two fixed and one guest ale on at a time, but I want to increase the offering to 2+2.  My bright, excuse the pun, idea is to decant a cask into 2 x 20l bag-in-box, these normally giving a longer shelf life.

If you do a search there is no consistency in advice as to how long it will last.  Some say 1day if you decant it bright, yet the same brewery also sell bright bag-in-box with a week shelf life.  I could decant it live and then let it settle in the bag.

Essentially I am looking to see if anyone has any experience of this and what sort of shelf life you get before dispense (I would imagine somewhere close to the BBD on the cask) and after you start dispense.

I already do it for some cask ciders and it works fine – sell both bags through in 3 weeks.

Any views appreciated.


  1. I cant tell you for certain but my limited experience is this. Beer when brewed is put in a cask and sealed. The product is I understand still live and will produce some Carbon Dioxide which will keep the beer “Fresh”. When the Cask is put into use CO2, Air and possibly nitrogen can be introduced. At this point the Shelf life is clocking up the Days.
    Sharps will sell a MiniKeg of Doombar with a shelf life of 5 days. This is similar to the life of Beer in a Bag in a Box. One good thing about Bag in a Box is the exclusion of any air. As the product is drawn out either by gravity or pump the bag colapses. If the bag was 100% full and no air is traped then it will last for the 5 days happily.
    Some breweries will supply products in a Bag in a Box. Sharps are one.
    I guess at the end of the day it is best to buy in smaller volumes more frequently and have a reputation of always serving a good pint, rather that having a reputation of not always haveng a decent drink. You only need to serve a bad pint once to a customer to ensure they dont come to you again.
    Finally I should mention You can get fittings which will go on the Bag in the Box tap and connect to a Hand pump without any gas to push it. Not all bag in the box taps may be the same so check first.

  2. Decanting cask ales is not a very good idea they are a live product with a specific blend of microbes which give the beer its correct taste, aroma and appearance. If you decant there is a very high risk you will contaminate the cask beer with wild yeasts, moulds and bacteria from your cellar which will spoil the beer giving taints. Once you have tainted your beer then you have no recourse to return anything to the brewery and you could end up with massive amounts of beer you have to pour down the drain ruining your profit margin.

    • i agree with the proton group, DONT DO IT, its not worth the time and effort, you stand a good chance of loosing the lot, try explaining that to the brewery, they are not daft, sometimes, I always say “if you have thought of it, so has someone else”.

  3. Ian – For the cider I vent, add a race cask, tap and then decant into 20l bag through a sanitised tube all within about 5 minutes. I put a rubber seal over the bag inlet that has a hole in the middle smaller than the tube – this minimises any air contact on decanting.

    Seti – Sharp’s, like may others sell their BIB bright – so it is not surprising the shelf life is shorter. But some others supply live ale and the shelf life is significantly longer, although you have to let it settle.

    Proton – Thank you, but all you are telling me is what can go wrong. What I am after is the art of the possible.

  4. Hi Devi

    Wouldn’t you have to make it bright to put it in a bag by filtering it anyway. If you left hops in it would keep on fermenting and the bag would expand and burst. That’s all the micros do I think, I know a micro who used to send them by courier but he gave it up in the end cause they where exploding in the depots. I think anything is possible it would be fun to experiment and if you are careful wastage should be minimal and has been mentioned before everything should be made sterile. This brewer reckoned he could get 10 days to 2 weeks, but I suppose it depends on the brew and how sterile your cask tap etc is . Good luck.

  5. Could ask breweries to provide beer in pins rather than firkins. What is your concern with not having a 4th 9g? The time to sell through or are you restricted by the tie? Because if its the latter youre probably breaking terms even with bag in box

  6. Hoppy – many thanks for this. Lets me know it is possible. The bags I use are self-venting, so don’t really have a ballooning issue. I only push the tap in one click so I can do some additional venting, but only had to do it once. I then push the tap fully home before I connect to the hand pull. I wish Weston’s used these bags as their Perry constantly balloons in the BIB they supply – although not went pop yet.

    Alex – I’m restricted by the tie, as I stated therefore can’t get pins and can’t sell through 4 but want to – as I also said. I’ve been in the trade a good number of years and know what the tie means and my obligations – this will not breach any tie I have ever signed.


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