Mike

My instinct as a professional microbiologist says proceed with extreme
caution if at all.

Everything I have read about tea packaging has told me that it is a hot pack
process anat it is usually pasteurized or loaded with preservatives (Sodium
Benzoate). The big unknown is what is the pH of brewed tea. What makes
beer so safe is that after fermentation the pH of beer is typically between
4.4 and 4.7, this combined with the alcohol and hop acids inhibits the
growth of pathogenic microorganism, particularly C. botulinum the organism
that produces the botulism toxin.

I have no knowledge or experience of the safety or efficacy of what I am
proposing below but if I were to bottle tea this is how I would proceed.
Brew the tea, sweeten and add lemon to taste, bottle and cap the bottles.
Then using a canning pressure cooker process the bottles as you would for
any low acid canned food.

If I wanted an "instant", ready to serve tea that I could make up rapidly
this is what I would do. Make up a very strong brew of tea, add sugar and
lemon and store in the fridge, this should last about a week. This can then
be diluted to drinking strength pretty quickly. A larger quantity of the
"concentrate" could be stored frozen for a greater period of time.

Be Safe - Cwrw-42.