The term water bath refers to the technique of placing a bowl or pan containing food in another pan filled with hot water. Water baths are used for several purposes: keeping food hot, melting food, such as chocolate and butter, and gently cooking or baking food. In recipes, the term water bath is used most often to refer to the method of baking delicate foods (such as custards, cheesecakes and bread puddings) with gentle, even heat in a pan of shallow hot water.

This method does not necessarily require a special piece of equipment. A water bath may be done with two baking pans of different sizes, one pan to hold the food and a second larger pan for the hot water. A double boiler is a type of water bath and is used on the rangetop to melt foods or to cook delicate foods, such as stirred custards and hollandaise sauce.