The cistern has been around for a long time and is a useful bit of kit, however, pre-1993, the capacity for these types of WC cisterns were 2 gallons (9ltr). This volume was reduced in order to save water consumption to an initial 7½ ltrs. Eventually it was decided to reduce it to volume used today which is 6ltrs. WC systems work with a thing called a “Siphonic valve”. Nowadays another design of valve exists that lifts to let water flow. This makes the WC cistern a modern piece of technology. Abbey Wood Plumbers are experienced in all plumbing jobs. The water used to fill the cistern was controlled by a float-operated valve, which sat floating on top of the water level. This would then drop when flushed as the water left the cistern and by doing so opened the fill valve at the bottom allowing the cistern to re-fill. Once the float raised with the level of the filling water it shut off the inlet valve and stopped the water.Flush Button(s):There can now be two flush buttons fitted to a modern cistern, the first is set to carry out a short flush (small amount of water) and the second is set for a longer flush (larger amount of water). They operate by using a two-rod system that releases the small and larger volumes of water as needed by the user. Siphonic Action:Wen the flushing water leaves a cylinder without the help of a mechanical action it is said to have a “siphonic action”. The water travels up and over a tube that looks like an upside down ‘J’ shape. The long leg then joins with the flush pipe whilst the short leg is open to the water in the cistern. When the air inside is removed, a partial vacuum is created. The action starts when a large diaphragm washer lifts and lets a volume of water discharge away through the flush pipe taking air to cause the partial vacuum. A Thamesmead Plumber replaces siphons.