Abstract: The present invention relates to a device for purifying water, the device being an elongated container having an inlet and an outlet and comprising succesive adjacent sections being a. a disinfecting area, b. a membrane or filter medium having pores with a diameter of max. of about 0.2.mu. and c. granular activated carbon. The disinfecting area is suitably a mixture of crystalline iodine with a suitable strong anionic exchanger, preferably in a ratio of 15:85.The device may comprise in addition one or more of the following section: a. filtering section; b. a microscopic filter having pores with a diameter of max. 0.5.mu. and/or c. bacteriostatic carbon.