Monobloc tap problem

I used an inline valve to control flow to a toilet cistern. Seems to have worked well enough for a few years

An in-line isolation valve will not reduce the static pressure. Test theory by putting thumb over tap and opening it only a little - eventually water will escape.

Well, put it this way, it stopped that thud in the cistern when the valve closed.

...yes - by slowing the flow. This would allow the valve to close more slowly. The pressure would be the same - once the flow had stopped.

The head of water is the same. (Water tower somewhere - or pumps)

Sounds as if the tap revivers are compression types with a coarse, helter-skelter-type thread to acheive a transition from closed to open in a quarter turn. These can get pushed open by water pressure: I had it happen on a pair of lever-type basin taps when I converted from gravity to mains pressure. I'd try ceramic-disk-type inserts instead.

I've come across exactly the same problem twice. In both cases I fitted a service valve & turned it down a little.

Despite being told by several here that it wouldn't work because they don't reduce the static pressure - it does work and has done in both instances for over a year.

Thanks for all your comments. I think i have fixed it by tightening the gland nut.

jonathan