Combine the water and milk in a large saucepan or small Dutch oven. Bring to a boil over high heat.

Stir in the oats and salt and allow the mixture to return to a boil. Reduce the heat so that the liquid maintains a gentle simmer, then cook for 20 to 25 minutes, or until the oats are thick and creamy. Stir occasionally, gently scraping the bottom of the pan to prevent sticking.

Remove from the heat and let stand for 2 minutes to continue thickening. Stir in any desired mix-ins, then portion into bowls and serve with desired toppings.