Maggots in Kombucha, Why you should never use a Cheesecloth!

Never Use a Cheesecloth for Kombucha Brewing!

A cover of some sort is needed for any home ferment. The primary function of the cover is to avoid contamination. Mould and fruit flies will appear in nearly every batch if left open to the air, as these tiny living things feed on the sugars present in young ferments.

So is the simple answer to always use a hard lid to cover your ferments??  And we can end here. Hope that was helpful. Just Kidding, lets dig into it.

In reality, rather than a hard lid, Kombucha almost always needs a breathable cloth cover. But a hard lid on your Kombucha could be okay, or even appropriate, occasionally? Other ferments, on the other hand, can use a hard lid or a water seal.

Yeah, it is a little more complicated. The good news is that once you've learned the rules, they're simple to follow. Even if you make a temporary error, switching to the proper form of cover would usually resolve any issues. Read on to learn how to choose the right cover for your ferment.

Never use a Cheesecloth! Unless you want Maggots in your Kombucha!

Cheesecloth is a big NO when covering a Kombucha Brew

The most widely shared piece of really bad advice is to cover a batch with

cheesecloth. It's never a good idea to do anything like this! Even if you fold the cheesecloth several times, fruit flies and other contaminants will still get into the brew, especially over time. Fruit flies are obnoxious and persistent, and they'll find a way in! Then they will multiply in your kombucha (lay eggs that will develop into larvae’s). I don’t know how about you, but I prefer to get my protein from other sources, I have a feeling you would agree with me on that.

Kombucha Cloth Cover

Aerobic ferments (Kombucha is one), as the name suggests, are those that require oxygen to thrive, typically at the start of the fermentation phase. Kombucha and JUN Kombucha are acetic acid-dominant ferments, similar to vinegar. As a result, it's best to brew them in open-top containers with a breathable cloth covering.

A new layer of culture develops on top of the brew as it progresses. The new layer (SCOBY) starts to restrict airflow to the liquid below, converting the aerobic ferment into an anaerobic one over time. The distinctive sweet and sour flavour profiles of Kombucha and JUN Kombucha are the product of this natural progression.

A breathable cloth cover is needed for Kombucha and JUN in order to allow air to flow.

Oh no, I used hard lid for my Kombucha! What do I do now?

Though not ideal, a few days with a hard lid is typically not enough to destroy a batch or culture. Kombucha is a strong beverage. However, the yeast can inevitably produce a foul odour in the container, which may result in off flavours or even mould. You can be able to save a stinky brew by simply switching to a cloth cover and adding a little sweet tea to re-set the process if you catch the error in time and there is no mould. All will be well if the taste and smell return to normal.

The exception of the rule, when can I use a hard lid?

If you're transporting the brew or Hotel to a new place, it's fine to cover it for a few hours or even days. If possible, do so at the end of a brewing period or during a brewing break. Covering a young brew with a hard lid can cause bad odours to develop more quickly. However, once any of the liquid has matured, the lid can be left on for longer periods of time without causing problems. Bear in mind that Kombucha has a lower viscosity than water, so keep the container upright and wrap towels around it to catch any spills.

It may be possible to store a completely mature SCOBY Hotel with well fermented liquid (no sweet tea added recently) with a lid for a few weeks without problem. If you're taking a long break from brewing your Kombucha, this will help reduce evaporation. However, we do not suggest leaving Hotels like this unattended for long periods of time, as they will inevitably develop the same stale and stinky yeast problems as hard-lidded brews.

Disposable Covers

Paper towels a short term solution for Kombucha brew cover

Although some people use coffee filters or rubber-banded paper towels, these choices must be replaced after each batch. Between sheets of paper towels, seams will stretch open, exposing the brew. A single drop of liquid can cause a void. When adding to or removing from the vessel, tears are easily created. When the rubber band is on the brew, it will stretch, causing tears in the paper covers. Although disposable covers can work in the short term, we strongly advise moving to a more long-term solution.


How to choose the perfect cover?

Deciding which is the perfect Cloth for Kombucha Brewing


There are a range of choices, as with all Kombucha Brewing Supplies, and each provides a unique experience. We prefer re-usable, because they are environmentally friendly. But the most important thing, of course, is security: keeping those pesky fruit flies out of the brew, as well as any mould spores or other contaminants.


Homemade Cloth Covers

The texture is the most important consideration when making a fabric cover. The best

choice is a fabric, which is smooth, thin, is breathable and has a strong weave. Never use a loose weave fabric like a muslin or cheese cloth. Also, stay away from kitchen towels, which are usually very thick. An old cotton t-shirt or bed sheets are always the best alternatives. Of course, if you would like to save you some time, you can choose one of the covers we provide Please see below.

Have the correct homemade Kombucha Cloth


Hope you enjoyed this read!

Happy brewing



  • Bob Kershaw

    All very instructive; and entertaining, too.

  • Karl Herber

    Thank you MOYA O’ROURKE

  • Moya O’Rourke

    Your advice on appropriate covers for Kombucha brews was very helpful.

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