In a large skillet, cook the ground beef over medium-high heat until it is no longer pink.
Add the taco seasoning and water. Stir to combine and simmer for 5 minutes.
Lay a tortilla on a flat surface. Sprinkle 1/4 cup of the cheese over one side of the tortilla.
Top with 1/4 of the cooked ground beef mixture.
Fold the other half of the tortilla over the filling and press down lightly.
Repeat with remaining tortillas and filling.
Heat a large non-stick skillet over medium heat. Place one quesadilla in the pan and cook for 2 minutes on each side, or until golden brown and cheese is melted.
Repeat with remaining quesadillas. Cut into wedges and serve.