If it is brewed at a high enough temperature, tea can keep for up to eight hours. Although foodborne pathogens can live in tea, brewing it at 195 degrees Fahrenheit kills those pathogens.
According to a 1996 memo from the Centers for Disease Control, as excerpted in Food Safety News, brewed tea itself has little to no history of disease transmission. The containers in which tea is brewed or stored and the faucets used to transmit the tea are more likely to carry germs than is the tea itself. Tea brewing and storage containers should be cleaned daily for safety.