Water treatment vessels and cartridges therefor

摘要

A water treatment vessel is adapted for receiving, in use, an elapsed time indicator (112). The vessel comprises denominating means, for denominating a portion of the indicator corresponding to a desired elapsed time, so as to allow a user to see when the indicator indicates the desired elapsed time. The denominating means may comprise one or more windows (110) such that only a selected portion of the indicator is visible. The vessel is arranged to activate the indicator (112) automatically when it is installed.