Fill a large saucepan with 4 cups (960 milliliters) of filtered water. Place the saucepan on the burner, and turn the heat up to medium. Wait for the water to come to a boil. If you want to have a more traditional tea, you can use an authentic Thai tea blend. It would be a good idea to check the ingredients, however, as some Thai tea blends contain yellow or orange dyes to give the tea that traditional orange color. Unfortunately, not all of these dyes are organic. Stir the tea with a long spoon or whisk until the sugar dissolves, then give it a taste. If it is not sweet enough for you, add some more maple syrup or sugar.  If you can't find any maple syrup, try agave nectar instead. If you can't find any muscovado sugar, try organic brown sugar or coconut sugar instead. If you are using an authentic Thai tea blend, you can skip the vanilla extract and maple syrup as it will have other flavors in it. Once the tea is cold, fill your glass with ice. Pour the tea into the glass until it is three-quarters of the way full. If you do not have any coconut milk, or if you don't like it, you can use another type of non-dairy milk. Vanilla almond milk and rice milk are both great options!

Summary:
Bring the water to a boil. Take the saucepan off the burner, add the tea, then let it steep, covered, for 5 minutes. Pour the tea through a fine, mesh sieve into a large pitcher, then stir in the maple syrup, sugar, and vanilla extract. Let the tea chill for 2 to 3 hours in the fridge before pouring it over ice. Top the tea with some coconut milk, then serve it.