Bring water to a boil in a large pot.
Add sugar and stir with a wooden spoon until it's all dissolved.
Add your tea bags to the water and let it steep for 10 minutes.
Once the mixture has cooled to room temperature, remove the tea bags and pour the liquid into a large glass jar or jug. Leave a couple of inches at the top.
Pour your store-bought kombucha into the jar.
Wash and dry your hands thoroughly. Gently slide in your SCOBY using your bare hands. Leave it as is, even if you think you should adjust it.
Gently place your kombucha starter kit (that's what its now called) somewhere warm, dark, and quiet, about 75°F to 80°F (24°C to 27°C).
Cover your kombucha starter kit container with a breathable cover such as a tight-weave cloth like clean cotton, a paper coffee filter, or paper towels. Do not use cheesecloth or an airtight lid.