I'm cooking soup as a starter for Christmas dinner. I've made this soup before and I used 1.5 litres of water for 4 servings. I'm making 12 servings for Christmas day so that should be 4.5 litres of water required if I just put in 3 times as much of everything.
I'm not sure if I've correctly scaled up the water needed, 4.5 litres sounds like a lot of water. Maybe when cooking 4 servings 1.5 litres of water is used but 0.5 litres boils off, then with 12 servings 3.5 litres is used and still 0.5 litres boils off. Is this a smarter way to scale up the water needed?
Edit: To make 4 servings I add 6 tomatoes, a leek and 3 potatoes; I simmer it for 30 minutes with the lid on.