WATER FILTERS; CARTRIDGES FOR WATER FILTERS; APPARATUS FOR TREATMENT, PURIFICATION AND FILTRATION OF DRINKING WATER; DOMESTIC WATER TREATMENT, PURIFICATION AND FILTRATION UNITS, FOR DRINKING WATER; WATER TREATMENT EQUIPMENT, NAMELY, WATER FILTRATION UNITS IN THE FORM OF BAR CARTRIDGES; AND WATER TREATMENT UNITS IN THE NATURE OF WATER BOTTLES COMPRISING TREATMENT, PURIFICATION AND FILTRATION FILTERS, WHICH ARE SOLD EMPTY