I've utilized many different methods of steeping for kombucha brewing, both at home and at Kombucha Brooklyn. Today I'm going to analyze the effectiveness of a few of those methods. I'll also suggest one that for the average home brewer may be the simplest, fastest and most efficient of those.
If there's one ubiquitous Western archetype of tea consumption, it involves the tea bag. Initially meant in the early 20th century to offer samples of loose leaf teas, the tea bag caught on and became very popular in use for making iced tea. My earliest memories of tea were of my dad using a dedicated coffee-maker to steep Lipton bags. He'd put the tea bags into the coffee carafe, pour water into the machine, and allow the hot water to flow down and immerse the bags for 3-5 minutes. After that, the tea was poured over lots of ice in a pitcher and thrown into the refrigerator.
Fast and easy
Some major advantages to the tea bag are simplicity and cost-effectiveness. It's very simple to toss some hot water on a tea bag, let it sit, remove, and enjoy. I can throw a bag of Earl Grey in my back pocket for consumption later in the day (which I've just done). Since tea bags usually have a string attached, it's very easy to control the steep time. For the producer, the bag is easily marketable as a simple way to drink tea, and it offers a way to utilize broken pieces of leaves like dust and fannings that are the by-product of loose leaf tea manufacture, thus reducing waste and making more tea available. Think "seconds" of apples or tomatoes at the farmer's market.
That's not to say there aren't loose leaf teas packaged in bags. My consideration for this lies in the effect this has on the tea, and how it's used by the consumer. On the whole, loose leaf teas are less dense than teas usually packed in bags. That means they will expand to a much greater size than will fine, broken pieces of tea leaf. As a result of the unbroken nature of the leaves, they will take up more space once steeping than will the tea generally packed in a tea bag. The more the leaves are allowed to unfurl and "give up" their flavor to the water in which they are steeped, the more flavorful will be your infusion. While this can be done with a large, reusable mesh bag, don't skimp on space - there's not much that's more depressing in the tea world than seeing a tea bag bulging with whole, unbroken leaves.
Respect the leaf!
So, tea bag or no, loose leaf teas have a lot to say and a ton of flavor to give up. Steeping them in the largest environment possible, unhindered by bag or walls will elicit the most flavor from the leaves. That is, to an extent - I wouldn't boil 10 gallons of water to make 10 gallons of kombucha, ever. Keep in mind also that loose-leaf teas should always be infused multiple times, with the longevity of flavor and color decided by the amount as well as the variety of tea.
For a kombucha brewer this would take the form of adding boiling water to your tea and allowing it to steep for 20 minutes or so; then, pouring off that first infusion and adding more boiling water, and allowing another 20 minute steep. This can be done as many times as possible until it seems there is no more nutrient left in the tea, as can be told by the flavor or color. Be vigilant that you aren't creating more tea than your fermentation vessel will be able to hold.
Respect and reciprocation
This attention alludes to a respect for the earth in not wasting its products, but also in reverence for the producers of the tea. Plucking tea is no simple task, and often takes place in locations that require climbing and balancing, as well as a trained attention to detail. Where the biological makeup of kombucha is the result of the symbiotic pairing of bacteria and yeast, so intertwined also is the relationship of man with the tea plant in the cultivation and preparation of tea leaves for consumption. Since in this day and age it can be nearly impossible to give back directly to the producer, at least get as much out of the leaf as is possible, and send out some aloha for all of the labor that went into getting it to you. Your 'buch will be that much tastier because of the good intentions that were incorporated during the brewing process. (Such observance with your standard tea bag might be steeping it twice, or maybe three times, and giving it a hearty squeeze after the last steep).
The big steep
You can always just dump your loose tea into a pot of boiling water, stir it around, and worry about straining later. Really this is the ideal, as far as the leaves are concerned, but really it makes more work than is necessary. You can use a strainer, but a strainer that will pull out all particulate will likely be difficult to clean - especially if it's made of metal (I have spent a lot of time cleaning metal strainers in my 'buch brewing days). So, you may choose to use a mesh filter bag to achieve the same end. The same issue arises, though, in that you're going to have to clean the filter bag, that while small can provide a bit of a challenge, if only by being slightly time consuming.
That's why my favorite way to steep tea for smaller home brews involves a French press. It's very easy to clean, efficient at keeping the steeping water hot, and easy to quickly empty and refill. Also, it allows me to get the most out of my tea leaves. For a one gallon brew, I'll add 12 grams of a nice loose leaf tea, and fill the 34 oz. French press 1/3 of the way with boiling water. I'll let that sit for 20 minutes, pour off the hot liquid, add the same amount of boiling water, and allow another 20 minutes.
Repeat one more time, and you've got 34 ounces of steeped tea ready and hot enough to dissolve your sweetener. This is a simple model for a triple steep, but you could easily draw it out over 10 steeps - you'll just want to make sure you aren't steeping too much tea so you've overfilled your brew jar. After stirring in the sweetener, add cool water to bring the temperature down, add your starter and SCOBY, and you're ready to let your 'buch fly. Always keep in mind your final volume - if you've steeped so much tea there isn't room for the starter and SCOBY, you'll have to pour some out - but keep that in mind for your next brew.
So, if you're brewing a lot of 'buch, using tasty loose leaf teas and herbal blends, invest in a French press. Your 'buch will be tastier and more robust, and that can't be a bad thing!