Put the water, tea, chai masala, and crushed ginger into a saucepan over a medium heat, and gently bring to the boil. Reduce the heat, and simmer for 3 mins.
Add the milk and sugar, bring the boil again, then reduce the heat, and simmer for 2 mins.
Remove from the heat, strain, and serve immediately.
Leftovers can be strained and kept in the fridge in an airtight container for up to two days, then reheated. It's not suitable for freezing.