Water pie is a pie which includes water as the main ingredient

Are you a fan of both water and pie? Look no further. I think I may have found the perfect treat for you. A water pie is "a type of pie which has water as the main ingredient", hence the name. Yes, you're very welcome, lovers of hydration and baked goods. 

From Wikipedia:

The pie is made by adding water mixed with sugar, flour and butter, and sometimes some spice such as vanilla or cinnamon, to a pie crust. The starch in the flour makes the mixture set and thicken, thus acquiring a custard-like consistency. Soft drinks such as Sprite may be used in place of water.