Abstract: A vessel or kettle for holding water has a first chamber from which water can be pumped though a filter into a second chamber. The pump can be gravity, manual or power operated. Cold water from the first chamber can be pumped though an annular filter of ion exchange resins into the second chamber where it can be heated. The contents of filter can be held in a replaceable porous bag. A meter can indicate the amount transferred, eg in multiples of a volume such as a cupful. The vessel can have a spout valve that selectively allows the first chamber to be filled or water to be poured from the second chamber. The first chamber and/or the pump can be external to the vessel. The pump can include non-return valves and a siphon system.