It is a small valve at the bottom of the column that needs replacing. You need to order the part from Roca.
Paul
July 2007
rubber at the bottom is not closing fully. hold the valve half way down and turn it, it will come apart and on the bottom is a rubber ring take it off and turn it round and clean any scale off then replace.
hi-spec plumbing
June 2007
Automatic Answer
We may have found other answers which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix toilets.