Preheat the oven to 325 degrees F. Place cupcake liners in the cupcake pans. Set aside.
In a medium sized bowl, whisk together the flour, sugar, cocoa, baking soda, baking powder and salt. Set aside.
Combine eggs, buttermilk, water, oil and vanilla in a measuring cup and lightly beat with a fork.
Add wet ingredients to the dry ingredients, and mix with a whisk or your mixer until combined and no streaks for clumps of flour remain. Batter will be thin. Scrape sides and mix for another 30 seconds. Fill each cupcake liner no more than 2/3rd full.
Bake for 22 to 25 minutes (you may need more time depending on your oven), until toothpick inserted in the center of the cupcake comes out with a few moist crumbs on it. Cool on wire racks for 10-15 minutes, then gently invert onto racks until cooled completely.