BWT filter cartridgesBWT Magnesium Mineralizer Refill filter cartridges can be refilled several times. This not only saves you additional replacement filters and household waste, but is also cost-conscious. The handling here is very simple: lever open the lid of the cartridge by pressing lightly against the handle, dispose of the old granulate, clean the cartridge carefully, fill in new granulate, close the lid, let it soak - done.