I've been regularly making dairy kefir for a long time and made some non dairy kefirs using the grains. But last year I was given some water kefir crystals and they've been great! I tend to mostly use them in the summer to make cool fizzy drinks to go with the evening meal. And in cooler weather I have successfully frozen them. As these drinks are fermented you might want to give them a taste before serving them to children as they may become slightly alcoholic. Mine have not done that so far but if they do you can try reducing the sugar and the number of grains.
The basic recipe that I use is 1/2 cup of sugar, 6 cups of water, 1 cup of water kefir grains, 1 tbsp lemon juice and some dried fruit, generally a fig or a tbsp of raisins. I brew this in a big glass jar for 24 hours in a warm spot in my kitchen. Then I strain off the kefir grains and remove the fruit and transfer the liquid to another big glass jar to flavour it. The grains go back into the first jar with fresh fruit and sugar water. If you find your end result is too sweet then try either reducing the amount of sugar you start the liquid with or brew it for longer (or both). As all kefir colonies will work differently you will need to experiment a little. So think of these recipes as a starting point for your own kitchen science experiments!
Rosehip and hibiscus
This pink drink is my daughter's favorite. I think more due to the colour than anything else!
6 cups basic kefir liquid
1 tbsp dried hibiscus petals
1 tbsp dried rosehips (or 6-8 fresh rosehips if you have them)
Add the dried herbs to the liquid. If using fresh rosehips, mince them slightly. Allow to brew for a further 24 hours in a warm, preferably dark spot before straining out the herbs. Bottle into seal able bottles (I use ones with a wired cap rather than screw tops to help prevent explosions with very fizzy batches) then drink after a further 24 hours.
Lime and mint
6 cups basic kefir liquid
2 tbsp fresh mint leaves
2 tbsp lime juice
1 slice of lime
I like to use lime juice in place of lemon juice when making the basic kefir for this recipe but you don't have to. Add the mint leaves and lime juice to the kefir water and brews as for the previous recipe. This is also very tasty with basil in place of the mint.
For this recipe I make a slightly different kefir water. It does leave your kefir grains with a brown tinge but this will do them no harm and will soon disappear.
6 cups water (5 cups cold, one cup hot)
1 cup kefir grains
1 tsp treacle
1/2 cup sugar
1 tbsp lemon juice
1/2 tsp baking soda
1 dried fig
1-2 cubic inches fresh ginger root
Dissolve the treacle in the hot water then add to the cold. Add the kefir grains, sugar, fig, lemon juice, baking soda and sugar. Allow to brew for 24 hours then remove the kefir grains and fig. Peel the ginger then either slice and add to the kefir water, or you can grate it and crush with some sugar to remove the juice then add that. When I'm making this for kids I tend to slice the ginger. Personally I like my ginger beer hot so I use plenty of ginger, grate and add the juice then put the grated ginger in a cloth infusing bag and add that to the jar. Just to get all the flavour possible! I also sometimes add a couple of cloves, a small piece of cinnamon stick and some black peppercorns. Allow to brew again for 24 hours before straining and bottling. I find that brews with ginger in tend to be more fizzy so open bottle with extreme caution!
A note on opening bottles.
As water kefir is a live drink the results can be quite varied. Some batches are more tingly than fizzy. Others are... enthusiastic! So I always open the first bottle of any batch over the sink. I also cover the top of the bottle with a tea towel to help stop truly over excited batches from decorating the ceiling. That only tends to happen in the height of summer when I've forgotten about a bottle for a few days, but be aware it can happen!