In a large bowl, combine the potato water mixture with the mashed potatoes. Add the sugar, salt and eggs and mix with a wooden spoon until combined. Sprinkle the yeast over the mixture and stir until incorporated. Add the flour 1 cup at a time, stirring with the wooden spoon, until the dough is smooth and only slightly sticky.

With floured fingers, gather the dough into a ball and place in a greased bowl. Cover with greased plastic wrap and let rise in a warm in place until doubled, about 1 hour.

Punch down dough, then pat it out into a rectangle on a floured surface. Flour your fingers as necessary. Cut the dough into 2-3 inch squares. Shape each piece into a ball by pinching all four sides underneath to seal. Place buns almost touching in a greased pan. Cover with plastic wrap and let rise until doubled, about 30 minutes.