What is the difference between milk kefir and water kefir?

The short answer

Traditional milk kefir originates in the Caucasus Mountains, with living kefir grains historically passed down through families and communities rather than manufactured or purchased -- grains are added to fresh milk, fermented at room temperature for roughly 24 hours, then strained and reused for the next batch. Water kefir is a genuinely separate tradition, using different grains called "tibicos" fermented in sugar water rather than milk, making it a dairy-free alternative. A 2025 review found consistent clinical trial evidence that kefir enhances gut microbial diversity and improves digestive health, though most of that specific research has focused on the milk-based traditional form.