1. Peel mangoes, cup the meat off the pit and dice it. Add mango meat to a small pot.
2. Add sugar, vanilla extract and water. Stir to mix.
3. Bring to simmer over medium heat and turn the heat down to medium-low to low. Cover, leaving a crack for the steam to escape, and cook for about 30 minutes. Stir occasionally.
4. Once it's cooked, strain through a fine strainer. Press gently on some of the meat to get juices out.
5. Allow to cool before diluting with 4 parts water to 1 part mango syrup. Store syrup in a glass jar with a lid.

To store for a longer period:

1. Wipe the jar rims with a moistened paper towel and put on the two-piece lids.
2. Bring water to a boil in a water bath canner, add the syrup jars (using the little basket that keeps the jars off the bottom of the canner), make sure that they are covered with 1-2 inches of water and bring back to a boil. Reduce heat somewhat (you still want it to be boiling though) and process for 15 minutes.
3. Remove the jars and set on a towel on the counter top to cool.