Water treatment devices and cartridges therefor

A cartridge for treating water, the cartridge capable of releasably engaging a water treatment device. The cartridge includes a housing, an inlet for introducing untreated water into the cartridge, an outlet port for egress of treated water from the cartridge, and a treatment media for treating untreated water The treatment media is in fluid communication with the inlet and the outlet port. The cartridge further includes a first tube having an inside surface, an outside surface, a proximal end, and a distal end, where the inside surface and/or the outside surface is a sealing surface. The cartridge further includes a second tube having an inside surface, an outside surface, a proximal end, and a distal end, where the inside surface and/or the outside surface is a sealing surface. The first tube extends from the housing and surrounds the outlet part. At least a portion of the first tube or the second tube surrounds the other such that a gap is formed between the first tube and the second tube.