WC cisterns today are slightly different from those fitted many years ago. Actually, the cistern is now, quite a technological innovation. Water flowing into the cistern was governed by an older type of float operated valve This lowered with the water level when the toilet was flushed, at a point this would open a filler inlet valve and allow the cistern to fill, then, once the float had raised with the incoming water to a pre-set level the water would stop, ready to flush again. Pre 1993, 9ltr (2 gallon) cisterns for flushing were used. However in order to conserve water, the volume was reduced, firstly to 7½litres and then on to the volume we use presently which is 6litres. WC systems worked by using a “Siphonic” device, but nowadays there is another design that consists of a valve that is lifted which lets the water flow. To discharge this from the cistern down into the pan, a device is employed that cuts off when the most effective volume of water has been discharged. West Heath Plumbers fit toilet systems.Siphonic action:Happens when water leaves a container with no kind of mechanical aid. It travels up and over a tube in the shape of an upside down ‘J’. The long leg joins to the flush pipe whilst the short leg is open to the water in the cistern. As the air is removed a partial vacuum occurs. This is started by a large diaphragm washer lifting and causing a quantity of water to discharge away through the flush pipe taking air and causing a partial vacuum. A West Heath Plumbers is familiar with these systems.NOTE:A two-button system is usually fitted to the cistern, the first is for a short flush (low volume) and the other for a long flush (large volume). These use a long and short rod arrangement which releases the small and larger volumes of water as dictated by the user.