A tablespoon is a non-scientific but very widely used unit of volume, which works very well in cooking, herbal medicine, etc. It is represented by a capacity of one tablespoon which varies from roughly 15 mL in the US to 20 mL in Australia.
1 If tea is properly stored, it can potentially last up to a year for green and black teas. White tea lasts about six months before it isn't as good in quality as when fresher. Stale tea (or bad tea) will taste flat, as if you're drinking paper.  Glass or ceramic containers are fine provided that they're opaque.
Does cold tea have the same health benefits as hot tea? How long can you keep the tea after steeping? Does iced or cold tea still have the same benefits? The best way to enjoy green tea is to steep a small amount at a time and drink it hot. However, due to the demands of modern lifestyle, this is not always possible. A 2001 study conducted by The Chinese University of Hong Kong discovered that you can keep your tea at ambient up to 7 hours, and still enjoy its antioxidant benefits. But first let me explain why drinking hot tea is preferable.