A method for treating a fluid by providing a raw fluid to a process tank. The raw fluid may be water having varying degrees of contamination or another type of fluid. The method further consists of adding an ion exchange resin to the process tank to form a raw fluid/ion exchange resin mixture. After the fluid has been sufficiently contacted with the ion exchange resin, treated fluid is removed from the process tank through a membrane filter located within the process tank. The method is completed by regenerating the ion exchange resin within the same process tank.