Thanks Tony
I have just done this, last time it was fixed by David Wilson homes as its a new build property, I have contacted them but as usual take forever to reply!
It was fixed like by replacing a ball inside the take ? I think, apparently they use cheap parts and they need replacing now...
Unsure of what is actually happening!
A few years back the same thing happened where the overflow was dropping water then became a constant flow, now 3 years later it's Happening again.
Anyone know what this could be and how to fix it ?
When I turn the hot water mains tap off the leak...