Scoby Hotel
It's a good idea to keep a few backup cultures in case a batch that you are brewing goes bad.
There are a few reasons your batch can become contaminated and here are a few examples:

• Organic teas

- Organic teas are grown in unstable environments and may contain contaminants.

• Organic sugars

- Most organic sugars are unprocessed and contain small particulates that can ruin your brew.

• Anti bacterial soaps

- Residue from antibacterial soaps can be harmful to your Kombucha since it is a beneficial bacteria. ( if used be sure to rinse well )

• Tap water, filtered water, spring water, R/O water, ect...

- Anything other than distilled water contains chlorine/and trace minerals which can cause mold.
Although you can use these ingredients there is always a small chance it will grow mold.
A small chance but none the less a chance about 5% of batches that are made with organic ingredients are contaminated.
• About 10% of kombucha brews  made with filtered water grow green, white, or black mold ...yuck!!!
• Almost all batches of Kombucha tea made with tap water go bad.
Personally I like using organic tea and sugar ..... So here is what I do:
Each time I brew a batch of Kombucha tea a new Kombucha culture / Mushroom grows!
I save my cultures in a glass jar with about a cup of Kombucha tea and cover with a cloth and a rubber band.
I call it my SCOBY Hotel.
Be sure to keep them in room temperature away from sunlight.
Check on them every few weeks to make sure they don't dry out, if they do just add a little distilled water.

• Kombucha mushrooms /cultures can last over a year if kept in the right environment.

So just in case it's a good idea to keep a back up!