Water Cans are a good substitute for carboy fermenter. These Plastic Demijohns are easily available, inexpensive and light weight. Unlike glass carboy, plastic water cans don’t break when handled roughly.

Today, we will talk about how to convert your water carboy into a low-cost fermenter. How to attach a DIY airlock to it. Crafting your own setup and equipment only increases the joy of a hobby. Last week we had talked about DIY sanitizer. A blowoff tube can be attached to commonly available airtight containers especially the water cans, milk cans (which have large enough mouth for easy cleaning), or pickle jars with airtight lids. Do read our article on the equipment checklist to understand the Dos and Don’t of making equipment at home.

bisleri can with airlock
5 from 2 votes

Plastic Carboy Fermenter

Today we will convert your water bottle a.k.a plastic carboy into a wine fermenter. Step by step guide to making a blowoff tube or a DIY airlock for fermenting home beers, wines, and toddy. Fermentation produces CO2 which needs to be vented out. However, if a proper airlock is not fixed then oxygen will come and oxidize the home beers into sour vinegar.
Prep Time15 mins
Active Time10 mins
Total Time25 mins
Course: Drinks
Cuisine: alcohol
Keyword: airlock, baloons, blow off tube, surgical gloves
Yield: 1 airlock
Cost: 50


  • drilling setup


  • 1 piece surgical gloves
  • 1 piece baloon
  • 1 piece RO tube or pipe
  • 2-3 drops quickfix or adhesive
  • 1 piece plastic bottle or container
  • 500 ml sanitized water


  • Making Alcohol at home is very simple. First step is to clean the fermenter
  • Add your wort (beer), grape juice (wine) or ganne ka juice (toddy)
  • Add some brewer's yeast of appropriate strain (0.5-1gm/liter) to kickstart fermentation
  • Now comes the most important step: To prevent oxidation of the fermentation over the next 2-3 days when the sugar is getting converted to ethanol. For this most recipe books will recommend a airlock. If you are unable to procure one use the following options

Airlock alternatives

  • Alternative 1: surgical glove. Cover the mouth of the fermenter (bisleri water can) with the glove. Gloves will inflate as it gathers CO2. Once it is inflated, you can release some CO2 (about 2 times a day should be sufficient). Alternatively, you can prick a minute hole in the glove so that the accumulated CO2 gets released on its own. Instead of a glove, you can use a baloon as well.
    bisleri can with airlock
  • Alternative 2: Blow off tube: Rather than using the standard S type airlock, for vigrous fermentation it is recommended to use a blow off tube. Essentially you make something like a hookah. Allow the CO2 made from fermenting ethanol/alcohol/beer/wine through a water filter. Water will allow the CO2 to pass through but not allow the Oxygen to enter back. Just remember to have sufficient quantity of sanitized water in the collection container.
    Water can with cork and blowoff tube
  • Alternative 3: If you are making a small batch of ginger ale or toddy, then you can make it in a 2.5 Liters pepsi or cold drink bottle as well. PET plastic is ideally suited to withstand pressure and as long as you are able to vent out the build up pressure 2-4 times a day, it should be safe. Keeping the bottles in a cool place (desert air cooler tank, air conditioned room or refrigrator) would slow up fermentation and slow down chances of too much CO2 build up.
    releasing pressure for pepsi bottle
  • Alternative 4: To use a proper airlock.
    s type airlock india
  • Alternative 5: Spunding Valve: You can get a valve and plumbing supplies from your local hardware store to make a DIY Spunding Valve. This allows you to do pressure ferment and retain natural CO2 needed for sparkling wine and fizzy beers
    Spunding Valve carboy
  • Alternative 6: A modified lid of your pickle jar with an inverted medicine cap (15ml for measurement of syrup/tonic) can also serve as a airlock.
    homemade airlock


Oxidation is one of the biggest problems in homemade beers and wines. You can buy toddy or turbo yeast from our online store and begin your journey.

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Condom or Balloon Airlock

balloon airlock home brew
balloon airlock home brew

Any balloon, condom or surgical glove can be converted into a wonderful airlock. If you prick a very small hole it will also vent off excess CO2 without risk of oxidation as well. It is widely used for yeast starter cultures and wet yeast transportation and long storage as well.


21 years of experience in Home Brewing and author of Arishtam (India's first homebrew Guide Book).