it depends what type of cistern you have.but in general.turn off the water supply to the cistern .then flush[this will tell you youve turned it off ie it wont refill]disconnect the supply and overflow [if it has a pipe that goes into the loo disconnect this. large nut from underside of cistern ] if it is the type that sits on top of the loo undo the bolts from the underside of the pan.remov.e cistern.turn it upside down there you find either a plate/bolts sticking out or a large nut.undo the large nut .this will release the syphon.replace and reverse the procedure. job done
johnboy
November 2009