Abstract: A portable water-purifying device comprises a primary disinfecting chamber (50) and a combined secondary disinfecting chamber and post-filter (30). Water to be purified can be scooped by means of a cover (12) into a receptacle (90) containing a pre-filter media (39) of preferably silvered activated carbon beneath a coarse entry filter pad (102). From that receptacle (90) the water enters the primary disinfecting chamber (50), flowing downwards through nine or so passage-forming segments (22) filled with a microbiocide (56), to effect primary disinfection, that is, to kill a substantial number of pathogenic organisms, but probably not all. Each passage (22) is at least three times longer than it is wide, to prevent channelling of the water through the microbiocide. Disinfectant from the microbiocide (56) enters the water as it passes through.