Question on my cold water supply

[newbiev]

Hi there, I was wondering if somebody could explain something to me.
In my property, I have a cold water storage tank in the loft.
The stop cock is located outside of the property, attached to the water meter. When I turn this off, the cold water supply is shut off straight away.

What I'm confused about is, is the tank in the loft being used? I would've thought that the stopcock would be located inside the house if there was an indirect supply.

Thanks

 

[rjm2k]

Is there water in it? Is it big or small, what kind of boiler do you have? Do ALL cold water outlets turn off at the same time, ie all taps, toilets etc?

 

[newbiev]

Is there water in it? Is it big or small, what kind of boiler do you have? Do ALL cold water outlets turn off at the same time, ie all taps, toilets etc?

Yes there is water in it, in the loft there is a big and a small one. The big one definitly has water as the overflow was leaking in the garden a few months ago (fixed now by plumber), not sure about the small one. Yes all cold water outlets turn off, apart from a few residual trickles that come through (I guess that's water emptying out of the pipes.)

As for boiler, I guess its a standard boiler, water is heated and stored in a cylinder tank in one of the upstairs cupboards.

Thanks

 

[CBF]

then it sounds like all your cold water is mains fed & the tank in the roof is just for your hot water cylinder