Abstract: A twin tank flush device, which comprises a first upper tank adapted for collection of wash water, and a second lower tank which is positioned to receive and store used wash water from the first tank, the first tank being arranged to receive water and having at least one outlet to discharge water into said second lower tank. The lower tank is arranged to selectively discharge the stored water either to a toilet to flush the toilet, or to a public drainage system, either manually or by timed discharge, to avoid overflow in the lower tank.