Toilet running intermittently

[louisa0891]

Why is my upstairs toilet running when i switch the tap on or washer/ dishwasher on downstairs?

 

[Deleted member 120897]

Is this a new fault or has it always happened?

 

[louisa0891]

Is this a new fault or has it always happened?

This is a new fault, it's was installed about 5 years ago & was fine up until recently.

 

[Deleted member 120897]

What is the make of float valve? Sounds like it’s just passing because it’s developed a fault.

 

[Joesson]

This is a new fault, it's was installed about 5 years ago & was fine up until recently.

We have Fluidmaster valves in two upstairs and one downstairs toilet cisterns. Recently, when we were away from home,our neighbour messaged us to say water was “pouring” out of an upstairs overflow.
I asked a key holder to flush the cisterns but the cistern refilled and overflowed again.
When we got home I was told that the Mains supply and been turned off in our road for repair work.
I could not get the valves to close other than by turning up the flow on our mains stop tap.
That meant that the cistern valves were not as effective at low flow/ pressure.
Maybe that is happening with the OP, the mains flow/ pressure is down and opening a downstairs tap is reducing the flow/ pressure to the cistern valve upstairs.
I would try turning the mains stop tap up a little to increase the flow/ pressure.

 

[Deleted member 120897]

Ah, so the plot thickens. Yes, could be the latter part of your description, could also be some debris stuck inside?