Stopcock - isolation valve leak

[Cubist]

Sorry I may have confused you. All your Hot Water services to the bathrooms and the kitchen will be supplied by your Combi Boiler. If turning that valve Off stops both the hot and cold water flow to those rooms then it MUST be the houses internal Stop Cock.

Those types of Isolation Valve you have there are prone to trapping grains of grit/sand or lime scales as the internal ball rotates in its body. Those minerals can damage the ball and or the walls of the valve body to induce a leak or simply stop it closing effectively. The older style Gate Valves using a different internal mechanism that pushes a piston down across the water flow to stop it. These are, in my opinion, better as they do not share the same problem. May be worth asking your plumber to replace that Isolation Valve with a decent Gate Valve.

 

[fernicarry]

In an emergency we were just going to go outside to turn off the water, but it’s a bit annoying that we can’t locate the main stopcock.

I recently replaced the stopcock in my son's flat in London and whilst googling how to turn off the new fangled smart meter in the pavement outside I also read that Thames Water expects you to have your own point of isolation and to not rely on theirs. Which does make sense. Being able to isolate individual parts of your system for maintenance is also good practice.

Your main stopcock could have been boxed in somewhere in the property. At home one of ours is in the wall behind the oven and is a royal PITA to get at. Also if its any age it will probably be thoroughly seized up so will need replacing too. That was the problem with my son's place. I was advised to leave the old one well alone (it didn't leak it just didn't turn) and put a new one in line with it which since I had plenty of space to work with was a 10 minute job.

Be sure to get a decent branded valve like Pegler for best chance of it surviving.

 

[my_name_is_slim_daisy]

Apparently you shouldn’t leave the lever idle for many years. Every summer and autumn move the lever a few times between the on and off positions

 

[lizziecupcakes]

Thanks everyone!!! Really appreciate the help so much. I had a chat with a plumber earlier and he helped me understand your comments too! Really happy to have him come over now to help with this.

 

[fernicarry]

Apparently you shouldn’t leave the lever idle for many years

Yes, that's a good point. Shades of "The Annual Oiling of the Hinges"...

I was also taught not to leave a gate valve completely open or completely closed, always back if off a fraction of a turn from the end stop. Whether that is an urban legend or not I don't know. I suppose its the same argument that sometimes tightening a bolt or screw slightly first breaks it free and allows it to come undone more easily.

 

[Cubist]

Yes that’s correct. The indoor one only switches off the water to the upstairs and the hot water.

I hoe your plumber corrected you on this already but... that's not possible unless it's a cold feed going to an immersion heater as well as the cold taps.

 

[a twig]

I hoe your plumber corrected you on this already but... that's not possible unless it's a cold feed going to an immersion heater as well as the cold taps.

It’s possible if it’s one cold water pipe that is doing all the upstairs cold feeds and taps plus the DHW feed for a combi