Toilet cistern feed pipe

[Alan16]

The flow to the cistern is slow but the flow to the nearby cold tap is good.
I have been advised that the slow flow to the cistern could be due to a number of reasons, including a partly blocked pipe, which is located behind the wall. Checking this would involve breaking tiles and retiling so my question is:
Could the pipe to the cistern be blocked off and a feed from the nearby tap supply pipe be routed into the cistern?
Pictures in album "toilet pipes"
Thanks
Alan

//www.diynot.com/network/Alan16/albums/

 

[JohnD]

Do you have reason to believe that the float valve in the cistern is working properly, and is free of debris and scale, and is not incorrectly fitted with a high pressure reducer?

 

[Alan16]

Do you have reason to believe that the float valve in the cistern is working properly, and is free of debris and scale, and is not incorrectly fitted with a high pressure reducer?

Yes, a plumber dismantled it and checked it .
I didn't think about the idea of changing the piping at the time.