I bought mine specifically for use with tea. Victoria mentioned making some sparkling tea, and that sounded so good that I bought a few bottles of sparkling water and started dropping some inexpensive sencha in the bottles as quickly as possible (to avoid losing the carbonation), capping them, and leaving them in the refrigerator for several hours to overnight. I liked my sparkling sencha enough on hot summer days to finally buy a soda stream, hoping the environmental impact of the refillable CO2 cylinders would be less than bottling and shipping all the sparkling water around.
I have played with doing it in different ways, and what I do now is
1 set up a porcelain gaiwan with some dry leaf, cover it with hot water, and let it sit a few minutes.
2 I take a sodastream bottle and add some cool tap water to it so I'm not pouring near boiling water directly into the plastic bottle.
3 with a funnel, pour the tea and leaf right into the bottle. Pour additional cool or room temperature water through the funnel to get all the tea into the bottle. Fill the bottle to the fill line.
4 Put the bottle in the refrigerator. Wait.
I often start the night before to have it ready midday if I know I will be doing hot work in the morning (e.g., serious gardening/yard cleanup).
5 carbonate the chilled tea with the sodastream, directly.
I ignore their warnings about carbonating water first and then adding flavorings only to the bottle after removing from the carbonator, because I'm not putting in sugar or particles of foods and I'm not worried about a bit of tannins building up on the spout.
6 wait a minute or two with the bottle sealed.
7 Pour through a strainer into a chawan or larger yunomi.
enjoy!
A few other points
How much tea to how much water?
I prefer my teas relatively dilute, so I probably use less than you will want. Chilling mutes flavors a bit, but it's also a single long steep, so you need to find your own balance for each tea and your taste buds.
What teas?
I love sparkling sencha, and sparkling gyokuro has been a really marvelous treat on one or two special occasions. My favorite right now is Norbu's Red Alishan Oolong, a spicy, fruity, darkly oxidized but I suspect lightly roasted gem that is no longer available (Greg stopped running his retail shop right before Coronavirus hit, and I hope his new venture is doing well). I've also found that genmaicha is acceptable this way, especially if I increase the leaf to toasted rice ratio; it's not brilliant, but it's my favorite way of using up the genmaicha that comes as part of my Obubu subscription, which otherwise sits for a long time. It doesn't appeal as much with an earthy puerh, although a fruitier plummier shu pu (lao cha tou) can be OK.
And inspired by the mention of root beer in another topic, I'm going to start playing with other herbal & spiced infusions/tisanes, and will report back here if I come up with anything special.
Hope that helps!