"Kefir grains" might not actually be grains at all, but this matrix of yeast and bacteria is pretty amazing. Look after kefir grains well, and they give you access to an endless supply of fermented probiotic goodness. Originating in the Caucasus region and still popular in such places as Russia, Turkey, and the Balkans, kefir grains are traditionally used to make milk kefir.  Though commercial milk kefir is available in some places, plenty of people also still use kefir grains to make kefir at home, pretty much all over the world.
Milk kefir does plenty for your overall wellbeing — the surprising health benefits of kefir include a boost to the immune system , antimicrobial properties , reduced cholesterol levels , better gut health , and even anti-tumor qualities . The fermentation process further means that milk kefir isn't just OK for most people with lactose intolerance, but that it actually helps your body learn to digest lactose better . Despite all that, the fact remains that not everyone wants to drink milk-based beverages.
Look around the web in places where kefir aficionados congregate, and you may notice that some claim that you can just as easily produce home-made kefir with soy milk, coconut milk, or almond milk. Many of those who write about this seem to lack personal experience, mind you. With a genuine little "kefir cult(ure)" going on in my immediate social circle after this one friend started spreading her newly-acquired kefir grains around, I now have access to a small group of people who can try things out — present company, of course, included. In the name of science and curiosity, I decided to try whether it's really possible to make kefir with non-dairy milk, and to ask some of my friends to do the same. Here are our results.
'Converting' Kefir Grains: The Process
In looking at why and how you can try using kefir grains to make water kefir, I discovered that you're supposed to rinse your kefir grains in mineral water (not unfiltered tap water, which can have tons of chlorine) to rid your grains of milk residue. After that, you pour your sugar-laced water into your container of kefir grains and let it all do its thing. Discard the first batch, and drink the second. Voila, you now have water kefir grains — which, by the way can't be converted back to milk kefir grains.
Figuring that making kefir with non-dairy milks like soy, almond, or coconut milk would work in a similar way, that is exactly what I did, along with three friends. A fourth friend agreed to participate in the experiment and decided not to rinse the kefir grains out. I personally decided to use a small amount of kefir grains set aside precisely for this experiment and to discard said grains after employing them for each batch of non-dairy milk. Everyone but the fourth friend, who decided to just go with her "regular batch" of grains (which she later went on to successfully use for milk kefir again; non-dairy milk kefir is different from water kefir in this respect) did the same.
Non-Dairy Milk Kefir: The Verdict
While the friend who didn't rinse her grains out said the end product tasted "positively vile" with the exception of coconut milk, which she kind of liked, the rest of us ended up with a product we considered potable. (I am not sure if she thought her kefir tasted foul because she didn't rinse the grains, or because she's picky.) The reported taste of each non-dairy milk kefir ranged from tangy like milk kefir to neutral or creamy without a tang. I personally enjoyed the almond milk kefir. One friend liked all of them, but blended with sugar and banana rather than on their own.
As a lacto-ovo vegetarian without lactose intolerance, I have no reason to avoid cow's milk myself. The tangy, effervescent, and honestly slightly addictive taste of milk kefir was missing from these batches of soy, almond, and coconut milk kefir. Non-dairy milks are also, as we all know, quite a lot more expensive than cow's milk. On the rare occasion I treat myself and my family to soy milk, I much prefer it in its original incarnation. In the name of actually enjoying what I drink, I'll keep on using cow's milk to make kefir, and drinking soy milk as is.
So, Want To Have A Go?
Milk kefir contains numerous species of lactobacillus, which require milk to keep going. In the case you convert your kefir grains to make water kefir, you're adding sugar and sometimes dried fruits, which then feeds your grains instead. This is common sense, really, but it's important to note that non-dairy milk will not go on culturing forever. We found out that you can make soy, almond, or coconut milk kefir two or in some cases three days in a row. After that, your kefir grains will die if you don't feed them real milk. Keep this in mind, and either set aside some grains for the purpose of making non-dairy milk kefir to discard later on (kefir grains proliferate like rabbits anyway), or make sure to give your kefir grains the cow's milk they're craving by alternating batches of soy, almond, or coconut milk kefir with batches of milk kefir. (If you're unwilling to drink milk, you could gift the milk kefir to someone who does want it.)