Whisk together flour, dry milk powder, sugar, baking powder, cream of tartar, and salt in a large bowl. Cut shortening into flour mixture with a knife or pastry blender until mixture resembles coarse crumbs. Stir water into mixture until uniformly moistened and a soft dough forms.
Turn dough out onto a lightly floured surface and, with floured hands, knead until smooth, about 8 to 10 turns. Roll dough out to 3/4-inch thickness with a floured rolling pin. Cut biscuits with a 2 1/2-inch round cookie cutter; place onto a baking sheet. Press dough trimmings together, roll out again, and cut remaining dough into rounds.
Bake biscuits in the preheated oven until golden, about 20 minutes. Serve warm.