This paper discusses the historical context and basic control theory of the temperature-controlled water bath, a standard piece of laboratory equipment used to heat samples over an extended period of time. The water bath system has a long history dating to the Industrial Revolution, and has developed into many forms over hundreds of years. Regardless of the design or function, the basic control theory involves the Stirred Tank with Controlled Heating Coil model with different kinds of controls for various additional effects. The aim of this paper is to present a brief history review and theory introduction about the water bath.