I have been making kefir water for several years now. Lemon kefir water has become my very favorite. Here is the link to my recipe for making kefir water. You use the basic steps shown in the receipe but instead of adding apple juice, you use a fresh lemon for flavoring.
Cut a few slices of lemon and add it to the jar after you remove the kefir grains.
After adding a few slices of lemon, I will squeeze the rind end to add some extra juices. Then put the lid on the jar tightly and leave it for a few days to ferment. Then remove the lemon pieces and refrigerate.
Kefir water is very useful and is a wonderful natural probiotic. Plus I just love the taste of lemon kefir water.