Not often one encounters a problem of no water management system in a refinery nowadays. Sometimes decades of ignorance may result in a poor or no water management in all aspects. Low water prices, absence of laws to comply with, lost of awareness, absence of policies, …etc. all are factors that lead to not implementing a functional water management system. In this article the water management system is treated as a functional system because engineers are familiar with the structure of a system of functions.To determine the functions of the system it is required first to determine the arguments of these functions.