Preheat oven to 350 degrees. Butter a 13x9-inch baking pan.
Combine the flour, cocoa powder, baking powder, and salt in a medium bowl.
In another bowl mix together the sugar, butter, and water. Stir in the eggs and vanilla. Once the sugar mixture is thoroughly combined, stir it into the flour and cocoa mixture.
Spread the batter into the baking pan and bake for 18 to 25 minutes or until a toothpick inserted into the center comes out mostly clean.
Makes up to 2 dozen brownies.