Place the hot water in a jug or single serve jars along with the tea and sugar. Stir to combine.
Let steep until cold.
Remove the tea bags and add the sweetened condensed milk. Stir until well combined.
Pour into serving glasses, add plenty of crushed ice.
Serve immediately.
Notes
Speed up cooling of the tea: One way you could speed up the process of cooling the tea is to sit the jug in ice while the tea steeps cooling it faster, but still allowing the tea bags to fully infuse.