Fermentation - Water Kefir


Water Kefir [kuh-feer] is a bubbly and probiotic fermented beverage made from sugar-sweetened water and any combination of fruits for natural flavoring.  The "grains," which resemble tiny pieces of cauliflower, are alive with a culture of beneficial bacteria and yeasts.  These microbes convert (ferment) sugar into acids, which are responsible for kefir's tangy, slightly sour flavor, and carbon dioxide, which gives kefir its refreshing effervescence.

Quick Reference (just the numbers)
 Water Sugar Kefir Grains
1 qt. 1/4 cup 1/4 cup
1/2 gal. 1/2 cup 1/4 - 1/3 cup
1 gal. 1 cup 1/3 - 1/2 cup
  • fermentation vessel (glass, plastic or non-leaded ceramic)
  • water kefir grains
  • wooden stirring spoon
  • sugar (do not substitute alternative sweeteners)
  • elastic jar cover (or cheesecloth and rubberband)
  • fine-meshed strainer (preferably plastic or non-reactive metal)
  • plastic or stainless steel funnel with tip small enough to fit neck of storage bottle
  • storage container (swing-top glass or plastic pop bottle to match batch volume)
  1. If using dehydrated water kefir grains, follow manufacturer's instructions for re-hydrating.
  2. Heat 2 cups water (doesn't have to boil, just hot enough to dissolve sugar).
  3. In 1-qt. jar (or similar), mix heated water and 1/4 c. sugar.  Stir until sugar is dissolved.
  4. Fill jar just shy of 1-qt. mark with cool water.  Resulting temperature should be between 20° and 28° C (68° and 85° F).
  5. Add water kefir grains to sugar-water mixture and stir gently.
  6. Place clean jar cover over top of jar, or use rubberband to hold clean cloth in place.
  7. Place jar in a warm spot (20° to 28° C), preferably out of direct sunlight.
  8. Allow to ferment 24-48 hours.  A longer fermentation time means tangier, more complex flavor.
  9. When the flavor is to your liking, the water kefir is ready to drink!  Strain the grains from the liquid and use to culture another batch of sugar-water (repeat process from step 2).  Or, if you prefer a bubbly beverage, proceed to step 10.
  10. Close bottle(s) tightly and leave out at room temperature for another 1 to 3 days (1 in hot weather; up to 3 when the temperature cools down).  Give your carbonated kefir a few days in the refrigerator before opening to allow the carbon dioxide to diffuse into the beverage.
Frequently Asked Questions

Can I use an alternative sweetener like honey, agave syrup, or stevia?

While many of us are trying reduce our intake of sugar, water kefir grains are definitely not; they need sugar to survive.   Alternative sweeteners like agave syrup, stevia, and Splenda do not provide the nutrients that water kefir grains need.  Honey may be used sparingly, in combination with another form of sugar, but it's naturally anti-microbial and could harm the kefir microorganisms.  Raw, or less refined sugars like demerrara and turbinado, provide trace minerals necessary to the long-term health of your kefir grains.  If you consistently use refined white sugar, occasionally adding a spoonful of molasses can boost the mineral intake of your kefir grains. 

What exactly is a water kefir "grain?"

Water kefir "grains" are made up of a symbiotic colony of beneficial bacteria and yeast held together in a loose matrix of gel created by certain of the bacterial strains.  These microorganisms consume and break down complex sugars into simpler sugars, lactic and acetic acids, and carbon dioxide.  As a probiotic, kefir benefits digestion and helps make certain nutrients more bio-available.

Is there any risk of glass bottles shattering due to the pressure of carbonation?

Yes, but with reasonable caution, you can certainly use glass safely.  Most glass bottles are plenty strong enough to contain a few day's worth of built up carbonation pressure.  If you know you have a particularly vigorous culture or the temperature in your home is high, your bottles will carbonate faster and could break if left out too long.  Also, just like when jars break during canning, it is possible for a scratch or imperfection in the glass to result in bottle failure during carbonation, so check your bottles regularly for warning signs.  The only bottle the author has ever had break was cheap and the glass was thin; the amber ones that were saved from commercial beers have never failed. 

It is wise to label your bottles or mark their start date on the calendar because if you forget how long your glass bottles have been out carbonating, you can't gauge the pressure inside except by opening them, which can lead to an explosive mess on your kitchen ceiling.  When in doubt, open bottles outside and never point them at yourself or others.  Plastic bottles are recommended for beginners because you can give them the "squeeze test."  When they're firm to the touch, they're ready to refrigerate.  If you forget to refrigerate carbonated plastic bottles in time, the seal in the cap is more likely to fail than the bottle itself and you'll just end up with leaky tops.

How do I use fruit to flavor my water kefir?

The above recipe is for a plain water kefir, the flavor of which will be sour and vaguely milky on its own.  The addition of fruit and/or herbs can greatly enhance the flavor of water kefir.  Most sources recommend waiting to add fruit and other flavorings until the second stage of fermentation, when the kefir grains have been removed, to prevent any unwanted contamination or damage to the kefir grains.  Simply place fruit and/or herbs into the bottles after straining out the grains, and remove before serving.

Additional Resources

http://www.culturesforhealth.com/water-kefir-frequently-asked-questions-faq    A much more extensive FAQ than we offer here, by the company whose water kefir grains we sell in our store.

http://www.deliciousobsessions.com/2013/02/lets-get-fizzy-with-it-your-water-kefir-flavor-guide/  A comprehensive flavor guide offering over 20 unique recipes from cherry limeade to mango colada.

http://www.culturesforhealth.com/water-kefir#beginner   Detailed information on culturing water kefir, organized by topics aimed at beginners and those with more experience.

Christensen, Emma.  True Brews: How to Craft Fermented Cider, Beer, Wine, Sake, Soda, Mead, Kefir, and Kombucha at Home.  An excellent reference for making all kinds of fermented beverages.  Especially of interest is the recipe for sparkling raspberry kefir wine on pages 63-4.

Water Kefir Supplies