Abstract: A water treatment pill is disclosed having a cylindrical periphery and disklike end faces and comprising material that in use is eroded to treat the water. The cylindrical periphery of the pill is covered with a cover of water impermeable material to prevent water coming into contact with the periphery of the pill. A passage is provided between the sleeve and the periphery of the pill and running from one end face to the other. This passage may be formed in the periphery of the pill or in the sleeve. One end face of the pill is closed off by a closure member. Thus with the axis of the periphery vertical and the closure member on the upper face of the pill, any gases which may accumulate below one end face of the pill can escape along the groove to the other end face.

Abstract: A water treatment device used in treating water in for example a swimming pool is disclosed. It comprises a blow moulded container which contains water treatment material comprising chlorine pills or portions of such pills and bouyancy means giving a bouyancy to the device such that when the container contains a predetermined amount of water treatment material, the container will sink to the bottom of the pool while the container will float on the surface of the water when it does not contain any pill material or only a small amount of such pill material. The container further comprises a skirt or similar support means located at the periphery of the container to support the container off the floor of the water containment. At the centre portion of the container base there may be a projection, which is part spherical in shape so that the WT device may rock slightly on movement of water therearound, the support means limiting the amount of such rocking movement.