In a small pot, bring the 3 cups water, milk and salt to a boil.
Slowly stir the grits into the boiling mixture.
Stir continuously until grits are well mixed.
Return to a boil, cover with a lid, lower the temperature to a simmer.
Cook for approximately 30 minutes, stirring occasionally.
Add the additional water a little at a time as you stir the grits.
Stir in the butter and serve.