Apparatus for descaling water; chiller units being parts of water cooling installations; devices for the separation of impurities from water (purification); electronic apparatus for the purification of water; installations for conditioning water; installations for waste water engineering; installations for water purification; installations for water treatment under osmotic process; machines for the treatment (purification) of water; reverse osmosis devices for use in water conditioning apparatus; reverse osmosis devices for use in water conditioning installations; reverse osmosis elements for domestic use in reducing the salt content of water; reverse osmosis elements for industrial use in reducing the salt content of water; reverse osmosis elements for reducing the brackishness of water; reverse osmosis elements for reducing the brackishness of water for domestic use; reverse osmosis elements for reducing the brackishness of water for industrial use; reverse osmosis elements for reducing the salt content of water; ultraviolet water sterilisation units; water conditioning apparatus; water conditioning installations; water filtering apparatus for industrial use; water filtration apparatus