Hi
I have turned off the mains stop tap in my house and all the taps have turned off... except one. Its an old outhouse cold water pipe (originally feeding the toilet which I have already removed). Its a lead pipe and goes down into a concreted floor, so I have no idea where it comes from. The stop value is just above ground level, so I can't see if it tees off before it anywhere. I have left it running for 15 minutes just to check it wasn't just water in the pipes, but the pressure is still high. I want to replace the very old stop tap on it with a modern one, but can't turn off the supply! Help!
Is this a plumber issue or a water board issue?