This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
If it is constant, and intended for use by many instances, why do you want several copies? If the value of BOILING_POINT is always 100, why should each Water object need its own copy? They can share the static field and save memory. It also means that BOILING_POINT is available to other classes without having to create a Water instance.