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!
In many old houses the supply from the street divides underground so the property has two stop taps. One in the house and the other in an outside toilet.
To work on either tap you need to shut off the main supply in the footpath (or wherever it happens to be) to stop the flow. You should be aware this may also effect your neighbour's supply too.
Don't do the work on a Sunday because until the pipe is cut and the new tap in place you cannot be sure what parts will be needed and not all DIY stores will stock bits. You may end up in the situation where a neighbours water is off and you can't turn it on!