Cigar Oasis water cartridges that clip on to the control unit contains a foam element with the distilled water and antifungal agent. The fan in the control unit draws air from inside the humidor and passes the air through the foam which is full of water and the air picks up humidity and delivers it to the cigars in the humidor. Water consumption depends on the size of the humidor, how good the humidor seal is and how dry are the cigars when you put them in the humidor. Typically, for a well-sealed humidor of 75-125 cigars that is opened 3-5 times a week, the water cartridge could last as long as 9-12 months. The water cartridge may be refilled once or twice, remember only with distilled water, but eventually the foam breaks down and holds less and will need more frequent refilling. Also with use the antifungal agent is depleted and eventually it is suggested that you replace the water cartridge with a new one, available from Cigar Oasis, Inc.                                                                                 Cigar Oasis miscellaneous accessories including Ribbon Cable, Connector for Ribbon Cable, Power Adapter for Cigar Oasis XL and XL Plus, Universal Power Adapter, Foam Brick for Cigar Oasis II XL and Auxiliary Fan.