Kombucha is essentially fermented sweet tea. That’s right all you southerns reading. Sweet tea - in a fermented form.
Water. Sugar. Tea.
Making Kombucha is as simple as brewing a big batch of tea the way you would for a Southern - cause if there isn't any sugar it’s just dirty water.
The thing that changes this sweet tea is something called a SCOBY or Symbiotic Colony of Bacteria and Yeast. Yummy! I know sounds gross which is why you just say SCOBY, but the process really isn’t any different than the fermenting and bubbling that happens with a sourdough starter.