Preheat oven to 325°F. Combine condensed milk and hot water in a large glass or metal bowl.
In a separate bowl beat eggs until light in color and fluffy in texture. Pour a bit of the hot milk mixture into eggs to temper, then combine them fully. Stir in vanilla and salt. Pour into ramekins and place on baking pan with high sides. Or use a 2-quart baking dish instead.
Place pan in oven and fill with half inch of water. Bake for 1 hour or until a knife inserted in center comes out clean. If using larger baking dish bake for 1 hour 40 minutes.
Allow custard to cool for 1 hour. Sprinkle with nutmeg and serve warm or refrigerate to serve chilled.