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.
Home > How to Store Brewed Tea. Once you store brewed tea in the refrigerator, you are essentially creating iced tea. The tea, whether black or green, should last for about two days in the fridge before it goes stale or flat. The Centers for Disease Control and Prevention recommends storing tea at room temperature for a maximum of eight hours.