In a small pot, bring the water, milk, and salt to a boil. Slowly stir the grits into the water. Stir continuously until grits are well mixed. Return grits to a boil, cover, lower the temperature, and cook for approximately 30 minutes, stirring occasionally.

Add the spinach in the last five minutes of cooking and stir in the butter. If they get too thick, you can stir in a little milk or cream.