Combine water, yeast, and sugar in a small bowl. Set aside until yeast becomes foamy.
If substituting the buttermilk, mix your milk and lemon juice together and set aside to thicken.
Combine the yeast mixture with 5 cups flour, salt, butter, and buttermilk or substitute until the dough forms a ball.
Knead the dough for 10 minutes. The dough is the right consistency when it feels sticky to the touch, but your finger comes off clean. If it is too sticky, then add a little more flour.
Transfer to an oiled bowl, cover, and let rise 60-90 minutes, until doubled.
Divide dough in half and place in greased loaf pans. Cover and let rise another 60-90 minutes, until doubled again.
Preheat oven to 375 degrees.
Bake for 15 minutes, turn, and bake for another 15-20 minutes until golden brown.
Let cool in the pan for 10 minutes, then transfer to a cooling rack.
Slice and enjoy!