Why does a creamy or bubble kind of white layer develop on water kefir & Why kefir smells bad or foul?

Instance 1 : Thin layer or creamy layer developed on the surface of the kefir

Sometimes we can notice a thin layer or film kind developed on the surface of the water kefir fermentation. This layer is called Kahm yeast and is the result of overgrowth of yeast than the good bacteria count. It is safe to remove the yeast layer before drinking.

We should always remember water kefir consists of a Symbiotic colony of good bacteria and good yeast, when the fermentation conditions ( your room conditions, air supply, humidity, hygenie, etc.) are favourable for excess yeast growth, we can notice this imbalance.

Instance 2 : Why does my Kefir drink smell bad or foul?

When there is excess growth of yeast balance, the kefir tends to smell very yeasty, foul with unpleasant taste. But, it is safe and harmless to drink. Within a few batches you can easily fix the balance of excess yeast as suggested below.

How to fix the excess yeast growth?

  • Excess yeast growth is directly connected to the oxygen supply, when we cut the oxygen supply by fermenting in anaerobic method (airlock lid fermentation), the excess yeast will get in control. Do not use cloth to cover the mouth of the jar, you should use an airtight lid to cover the mouth of the jar. Within 5-6 batches you can see significant reduction in yeast growth.
  • Gently rinse the grains with clean drinking water within a strainer. Usually the yeast and bacteria colony resides on the surface of the kefir grains, gently washing will eliminate the excess yeast from the surface.
  • Clean the jar thoroughly with warm water after each fermentation and use lemon juice to wash the jar occasionally. The yeast stuck in the jar sides will multiply quickly.
  • Room temperature is very important, place the jar in the coolest place of the house.
  • Change the sweet water frequently.


Kahm Yeast and Mold formation is different. Mold formation is like pinkish, greenish or some weird color with some hair kind of growth and solid mass look on the surface. You should discard the whole batch immediately.