Modular filter cartridge rack and method for operating the same

A modular filter cartridge rack is provided for holding a filter cartridge in place and the filter cartridge can be quickly detached from the rack or quickly mounted onto the rack. The filter cartridge includes a body having two opposite ends each having a first stub and a second stub longitudinally extending therefrom. The modular filter cartridge rack includes a main body having two opposite ends respectively having a first connecting device and a second connecting device extending therefrom and linearly corresponding to each other. The first stub and the second stub are respectively water-tightly and quickly detachably mounted into the first connecting device and the second connecting device. The water is filtered after flowing through the first connecting device, the body of the filter cartridge and the second connecting device.