I recently moved to a place that doesn't allow brewing equipment to be imported (But it is legal to brew... don't ask me). I've built a lot of my stuff, but I have a question about airlocks. I've come up with two ideas.

1) Simply running some tubing into a cup of sanitized water.

airlock 1

The problem I have with this is that I am worried about the tube slipping out or the water evaporating.

2) Curling some tubing into circles and adding sanatized water into the bottom of the tubing. airlock 2e

I can accomplish this one easily with some thicker tubing and zip ties, but I am worried that is won't function as well as number 1.

I want to design one that I can use many times over. Does anyone have experience with homemade airlocks or feedback on the two designs.

  • 3
    Of course the tubing doesn't go nearly that deep into the fermentor though; otherwise you'll be pushing beer out of the tubing.
    – brewchez
    May 23, 2011 at 15:23
  • 2
    Indeed, sorry for the inaccuracy of my drawing. I did those quickly just to post a descriptive image on here.
    – Beaker
    May 24, 2011 at 1:16
  • 2
    Yeah, I figured. I didn't want to seem like an ass, but its important to clarify because someone might not get it.
    – brewchez
    May 24, 2011 at 11:43
  • 1
    Oh no, I get it. And I appreciate any cautionary comments as I am still a novice :)
    – Beaker
    May 25, 2011 at 1:40
  • 1
    this person is genius thanks a lot very helpful and simple
    – user2645
    Aug 24, 2012 at 23:20

5 Answers 5


I use the first option for all my carboys and conical fermentors. I have not had a problem with evaporation or loss. Like your recommendation, I do use zip ties to secure the blow off tube to the bucket as well as using water with a diluted sanitizer solution in it.

The second option would make me nervous as a vigorous primary may blow out all the water or even worse, it may get sucked in when you are racking, moving it, etc.

Do the first 'blow off' option and think about a couple of things:

  1. How you are going to secure the tube to the fermentor (I use a plastic hood w/ zip ties)
  2. Will you need to expand the solution to include thermowells for temp control, racking & siphoning, etc
  3. How to secure the blow off tube to the blow off bucket
  4. Sizing the tube and blow off bucket to handle very active fermentation. I am always amazed how much gets blown off when you push the volume of the batch in the fermentor
  5. Remember to yank the tube out of the water when you siphon / rack off (otherwise you may draw in blow off water)
  6. Don't drink the blow off water even if it smells amazing :)
  • 2
    +1 I use a blow-off tube for every brew, regardless of headspace.
    – JoeFish
    Aug 25, 2012 at 12:48

I think for option 2 to work you would need a pretty substantial diameter hose (I'm talking garden hose diameter or larger). From my experience with siphoning tubes, air bubbles usually have a very hard time getting around liquid in a narrow tube.

Option 1 is used by a lot of brewers, as Peter indicated, so I would be more inclined to go this route. You could secure the tube with zip-ties, duct tape, or anything else that can hold it on.

  • 1
    I had considered a 1 inch diameter aquarium tube, which I did find over here. But I think with what peter mentioned, option 1 is the better solution. Thanks!
    – Beaker
    May 24, 2011 at 1:15

This may sound weird, but a bong is basically an airlock, the water is used to cool the smoke. Any waterpipe (hookah, nargili) can be used. Any glass or metal tube (like a cigar tube) can be used with a two-hole stopper to make one. Put two pieces of glass tubing in the holes in the stopper, one lower than the other. Fill the cigar tube with water so that the bottom of the lowest glass tube is under water and the other is not. push the stopper into the cigar tube to seal it. Connect the tube from your carboy to the one glass tube that is "underwater". viola, an airlock. cheers.

  • 1
    WHATS A BONG? LOL, sorry that was too easy! Aug 29, 2011 at 19:11
  • I’m 12 Years Old and What is This?
    – jessecurry
    Aug 29, 2012 at 1:37

I use a design very similar to figure 1. Where you use an jar I use a 2l plastic fizzy drinks bottle. I stabbed several holes in the top with a sharp knife. I then fed several tubes which have been inserted into corks and sealed up 1 gallon demi-johns into the holes i stabbed into the drinks bottle. The only limit to how many demi johns that can be attached to the air lock is the amount of tubes you can pass into the bottle.


You can also add a Non-return valve, just like the one used for cold water supply line of water heater, put it at the end of the tube, it will prevent water flow back to the frementer, it can be found at any plumping store

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