Is it safe to reuse loose tea leaves the next day? What precautions need to be taken for storing tea for reuse?
Here in China, it is normal to reuse tea again and again. Typically the first cup from the tea is bitter. Chinese people commonly pour one cup and then throw it away and drink the second cup from the same leaves. Workers here can be seen with a large mug or jar of tea. When drunk, they top up the water again with hot (but not boiling) water. This will go on all day.

The next day, however, they will not reuse the tea. My Chinese wife always tells me off if I reuse the previous days tea leaves. She says they are bad for you, though I have never had any problem myself.