Airlocks are your first line of defense against both oxygen and undesireable micro-organisms that can ruin your wine. Be sure to keep a close eye on yours.It’s inexpensive, easy to use, and easy to neglect. The cost of neglecting it, however, is all the wine your making. So what is this little savior of wine? The airlock.

Why Are Airlocks So Critical?

First, they keep out all of the undesirable micro-organisms that seek to ruin your wine. Vinegar bacteria, lactic bacteria, and weak wild yeasts are all kept at bay with a properly maintained airlock.

Second, airlocks prevent oxygen from entering your wine. Not only does this prevent oxidation it makes the production of alcohol possible.

As I mentioned in my post about the yeast fermentation process, yeasts only produce alcohol when it consumes sugar. This is only possible once they’ve run out of oxygen. Thus it is critical that a properly set up airlock is used to starve the yeast of oxygen so they’ll produce alcohol.

Now that I’ve shown you how important it is to properly setting up an airlock let’s get into how to set one up.

Why do Winemakers Neglect Airlocks?

Airlocks are put in place when the wine needs to sit for a while. Generally they’ll be in place for as little as a couple of weeks or up to a few months or more. Many winemakers will “set it and forget it”.

The hard part is done and now it’s time to give our wine a little time to itself to ferment or age. Many will just walk away and trust that it’s functioning properly and nothing will happen to it.

However there airlocks can fail. All it takes is an overly active fermentation, an improperly seated plug, or a cat to make unseat an airlock and let int oxygen and some nasty micro-organisms. When that happens all that wine will have to go down the drain.

How To Use an Airlock

In the following four minute video I’ll walk you through the entire process of setting up your three piece airlock. These are not the only type of airlock on the market, however, they’re the ones with the most moving parts.

Watch this video to make sure you set up your airlock properly. If you follow these steps you’ll be well on your way to making the best possible wine with whatever raw materials you started with. The price for not following these steps so is just too high.

Pretty easy right? Yes, BUT, don’t take these little devices for granted! They may be simple but they’re our guardians against spoiled grape juice.

Remember These Tips

  • Clean and sanitize every part of the airlock and plug.
  • Fill airlocks with only clean water.
  • Check on your airlock every day!

Here’s a link to the same three piece airlock I use to make my wine. This is an affiliate link so if you use it you will be helping to support Winemaker’s Academy.

  • Cindy Kelly

    What happens when wine comes into the airlock

    • Hi Cindy!

      Great question. Usually it is the foam from fermentation that gets up into the airlock. When that happens all the bubbles can force the water up and out of your airlock leaving your wine unprotected.

      This is only an issue when your wine is in primary fermentation and things are really happening fast in there. After five days or so you should be in the clear from this issue. You should still keep an eye on the airlock though in case the plug wiggles out or evaporation of the water becomes an issue.

      I hope this helps! Please do fire away with any other questions you have.



      • Barry Robert Slater

        can I ask a question about the direction of the gases in the airlock chambers?
        my single piece s-airlock sometimes goes one way showing that the wine is still off gassing, i.e. fermenting and producing co2. other times it is sucking in, is it seeking gas for some purpose? it is almost time to bottle the 2 year old wine so it is a moot point, but I would like to know more about the other side of air lock behavior. thanks

        • Hi Barry,

          I’ve seen this same thing happen to me and I believe it happens mostly due to temperature changes. Fermentation is exothermic so it is a process that produces heat. After fermentation ends and carbon dioxide production stops the wine temperature falls and the air inside the fermenter cools and contracts. Temperature swings can also occur simply due to changes in the temperature of your home from season to season.

          It’s best to try and equalize the pressure before the water in the airlock is pulled to the point that it drips into your wine. Some winemakers like to add vodka to the water in the airlock to keep it free of micro organisms in case it does drip into the wine. If you do this you will need to watch the water levels as the alcohol will evaporate more quickly than plain water.

          I hope this helps Barry!
          -Matt Williams

          • Barry Robert Slater

            thanks matt
            makes sense as the temps change so does the level in the airlock, the cooler air is denser & compressed drawing the atmosphere in. not likely a product of micro organisms craving oxygen

          • Often micro-organisms will produce carbon dioxide as a bi-product of whatever spoilage they’re causing so I would expect more bubbling as opposed to reduced internal pressure. It sounds like your wine probably just cooled off a bit. Cheers!

          • Barry Robert Slater

            must be it’s time to bottle this clear pale pink saskatoonberry wine,

          • Bill Wise

            I too have wondered about changes in pressure on the S style locks. My theory was barometric pressure. When it has negative pressure it doesn’t last too long. Just thought I would share….

  • Michelle

    Why do we put water in the air lock? I was told to keep an eye on it and make sure I always have water in the air lock, but I may have forgotten the why of it when I was on information overload.

    • Hi Michelle!

      The water in an airlock serves as the barrier between your wine and the outside world. An airlock without water in it doesn’t provide any protection.

      During fermentation the pressure inside your fermenter will build up until the carbon dioxide is pushed through the water and escapes. Oxygen is prevented from entering your fermenter because the pressure outside will always be less than the pressure inside during fermentation.

      I hope this helps!

      Matt Williams

  • Troy

    I’m currently producing my first attempt at making mead. I have followed a basic recipe and using a three piece bubblier airlock. It’s been 48 hrs since mixing the batch; however, I only notice very tiny/micro bubbles in the airlock. I guess I was expecting St. Elmo’s Fire and bubbling like a tea pot. Is this subdued manner of CO2 release normal… or has something gone wrong with my batch?

    • Hi Troy, this is a great question. Mead making is very slow. Honey is actually pretty hard for yeast to ferment into alcohol so it takes much longer than making wine if you’ve done that before.

      I’ve made meads that took two months or more to finish fermenting. From there it can take the better part of a year to clear.

      Usually you’ll only get a really aggressive fermentation is if you use something strong like a champagne yeast (EC-1118 in my experience) with plenty of yeast nutrients and in 70 degrees F or warmer conditions.

      Otherwise it is quite normal to see a very slow progression of small bubbles. It does help to stir up the yeast on the bottom of the fermenter every day or so during primary fermentation. I’ve always found that when I do this it not only stirs up the yeast but also gets some of the suspended carbon dioxide out.

      Because the fermentation is so slow the carbon dioxide produce tends to stay suspended in a liquid form. If CO2 levels get too high the yeast will begin to struggle.

      So far it sounds like you’re on the right track and can expect a laid back fermentation that will take a while to complete. When in doubt, with mead, wait longer and ask other mead makers what they think too.

      I hope this helps Troy. Cheers!


      • Troy

        Thank you, Matt… applied a gentle “stir” this afternoon. Best to you

  • Hi Glen, most winemaking recipes and instructions have you put the lid and airlock in place as insurance against spoilage. You don’t need it during primary fermentation when things are rolling along vigorously and there’s plenty of carbon dioxide being produced. However, there’s not a clear indication as to when the vigorous primary fermentation is over just by looking at the wine and most worry that they’ll put the lid and airlock on too late, exposing their wine to oxygen and potentially spoilage micro-organisms. So the safe thing to do is just use the lid and airlock even if you don’t need it for the first bit of fermentation. If you’re comfortable running without the lid then go for it.

    Personally I still prefer sealing my wine. Mostly I enjoy monitoring the airlock to gauge how fermentation is going. I hope this helps Glen!


  • colette geoghegan

    Hi matt. 1st time making wine from a kit. The wine is fermenting away but this morning the airlock had overflowed wine in it. I wasnt sure what to do so i topped the airlock up with clean water. Should i have disconnected it, cleaned and filled it back up again. Complete newbie here seeking advice

    • Hi Colette, great question! It is a good idea to detach the airlock, clean and sanitize it, then put it back in place. Also, take the time to sanitize the outside of the fermenter so you don’t get micro-organisms collecting where the wine was. Hopefully fermentation has calmed down a little bit and you are not longer at risk for the foam / wine to push through the airlock.

      Please feel free to ask as many questions as you like!


  • Bill Wise

    Matt, I accidentally only put 5 gal of water into my 18L W.E. Argentine
    Malbec (w/skins) kit. I didn’t go to the rim in the bucket, I went to
    the 5gal bold markings…. My SG was 1.106 at the start. When I racked
    it into the carboy for 2nd ferm I wondered why I was so low… Well I
    finally figured it out today! The SG was .996. Should I care at this
    point? Will it just be a VERY heavy wine? Should I add water and if so
    when? I still have about 5 days until time to degas. Thanks for your

    • Hi Bill, great question!

      As long as you wine tastes good I don’t think you have to worry too much about the missing water. In fact, some kit winemakers leave out 1/2-1 gallon of water to help concentrate flavors and increase alcohol content a bit.

      I would be wary of adding water after fermentation as your wine won’t be as well integrated compared to having added it at the beginning. Having topped up with water myself in the past I can say that my wine was not better for having done that.

      Taste testing is the best way to go. If it really is too heavy and intense you can add water but do it slowly, stirring and tasting it between each addition, and stop when you’ve taken the edge off. Again, I wouldn’t if it tastes okay now.


      Matt Williams

  • Brittany Elliott

    Hi Matt, I am looking forward to making my very first batch of wine soon, but I am confused about one step. Many tutorials that I have read attach the airlock immediately after mixing in their sugar and yeast, but other sites instruct you to only cover the bucket with a towel to allow airflow for a while first. Which is correct? Which is better? Won’t leaving the wine open to oxygen potentially contaminate it? My goal is to make tasty wine for long term storage (future Christmas gifts). Thanks in advance!

    • Hi Brittany, great question! I highly recommend attaching the airlock for your first wine. It is possible to ferment with open containers but you have to be able to determine when fermentation has slowed down to the point when you’ll need the airlock. This comes with experience.

      The idea of open fermentations is to allow a little oxygen to interact with the wine while the yeast population is still growing. A good amount of carbon dioxide is being produced at this point and it serves to protect the wine. At some point though CO2 production falls and your wine will be vulnerable. An air conditioning vent could also blow the CO2 blanket away if you’re not careful where you place the wine.

      When fermenting red wine with the grape skins all the skins float to the top to for “the cap” which also serves as a buffer between the wine and the outside world.

      For your first time out I think it’s best to use the airlock. That way you can focus on the rest of the winemaking process without having to worry about whether or not your wine is getting too much oxygen exposure or if spoilage micro-organisms are finding their way in.

      Best of luck with your first batch of wine! Feel free to ask as many questions as you like. The Academy community and I are here to help. Cheers! -Matt

    • Hello again Brittany. After answering your question I decided that this was a topic that needed thorough examination and so I wrote an entire article on whether or not you should ferment wines in open containers. Here’s a link to that article: