how do you fix cistern that leaks during flushing?
The leak comes from the bottom of the cistern. The toilet still flushes okay. It only leaks during the flushing not at any other time.
The make is a Qualitas of England

Michael, November 2007

The base of the cistern must be level. If like me you tilted it by screwing it to the wall you will spoil the seal . Coat the new doughnut washer with plumbers seal (from wickes) top and bottom and the top of the pan then tighten the wing nuts evenly.When screwing into the wall make sure the cistern does not tilt. I was surprised that such a small tilt could cause a leak as the water pressure is much less and the washer is so thick.

eddie from leeds, February 2010

Fit a new doughnut washer, spread silicone sealant where it fits against the toilet pan. B&Q don't sell them separately from the complete close coupling kit but Wickes do!

John, November 2007

fit a new donut washer in between cister/pan
as already mentioned.

hi-spec plumbing & heating (essex), November 2007

check the seal between the cictern and the bowl for wear, And make sure it is a tight fitting..

billyggla, November 2007