What does pH have to do with brewing kombucha? Ensuring your kombucha pH is correct is a crucial part of the brewing process. The purpose of brewing kombucha is to develop the good bacteria so the pH must be low enough to act as an antimicrobial solution which prevent growth of the bad bacteria and mold. Instructions: 1. Take a strip from the pack and wet it with the kombucha solution. 2. The strip will instantly change color. 3. Match the color of the strip against the color chart provided. 4. The number next to the color on the chart is your pH. Kombucha target pH. Kombucha Starting pH - 4.5 or less. Finished Kombucha - 2.5 - 3.5 but under any pH under 4 is still safe.