About 48 hours into my ferment I noticed a significant amount of liquid (about an inch) is missing from my airlock. Reading up on the subject I've realized that water was probably sucked into my brew due to a temperature change overnight. I used plain, unsanitized tap water to fill my airlock so I'm worried my batch could become contaminated. The water level on my airlock (three piece style) has dropped to just below the little holes near the bottom.

Does this mean my airlock is no longer providing a seal?

I'm not sure how long it has been sitting like that so thats another worry for contamination.

Should I refill it with more tap water?

I'm worried that if I do more water could be sucked in, providing more chance for infection. Sorry for all the questions first batch here.

  • 2
    Don't over fill the airlock, it will try to suck back again when you remove the cap later. This is why I prefer S-style airlocks: they work equally well in forward or reverse.
    – Pepi
    Feb 25, 2015 at 1:59

3 Answers 3


Your beer will most probably not be infected. Yeast are quite aggressive at this point in the fermentation and will kill any bugs that fell in.

I use vodka in my airlock. It guarantees that no bugs will get into my beer! :) I have used my sanitization solution before.

Just fill your airlock to the line (usually about halfway) and you are good.

Another note the airlock is there for a few reasons; primary being keeping bugs out, secondary to provide an escape for the CO2 that the yeast is producing. The CO2 will provide a blanket on top of the beer and also protect it to a degree.

Happy brewing.

  • 1
    I have used sanitizer, vodka and water. Water works as well as anything else.
    – Denny Conn
    Feb 26, 2015 at 16:17

No problem on either the water getting sucked in or the low level. Just add more water.


I typically use sanitization solution diluted with a little bit of water in case of this situation, but you shouldn't really have a problem.

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