How to turn off cold supply to toilet

[fjs]

I have a property with close coupled toilets.

To change the syphon on the upstairs one, I turned off the mains water, opened two cold taps, and drained the water manually before proceeding with the job. Not a drop of water emerged from the pipework.

Downstairs, on the toilet immediately below the upstairs one, I want to replace the inlet valve with a copper tailed one. Following the same procedure, the water does not stop. I had a similar problem when working on the ball valve in the cold water header tank at the highest point of the system. The cold water keeps flowing. Last September, the water meter was replaced. The mains water stop tap does not leak, or did not leak then. Other than the gate valves on the low pressure cold and to the hot water cylinder, there are no taps or valves on the system.

For the toilet, is it worth going into the roof to close the gate valves on the low pressure cold feed?

 

[Masood]

It is possible that the WC cistern is tank fed so turning off the mains would not isolate it. It would have to be done from the gate valve on the cold water storage cistern in the loft.

The cold water storage cistern is mains fed, so if water kept flowing after you turned the mains off there is a problem somewhere! Have you double-checked that the main stop valve isn't letting by? Turn the valve off and see if water still comes out of your kitchen cold tap.

 

[fjs]

Thank you. No water comes from any of the downstairs cold taps if the mains stop tap is closed. When the water meter was replaced, not a drip passed through it. I shall experiment by trying to turn it off more forcefully.

 

[Masood]

Thank you. No water comes from any of the downstairs cold taps if the mains stop tap is closed. When the water meter was replaced, not a drip passed through it. I shall experiment by trying to turn it off more forcefully.

No - don't do that! If you force it, it might break. If no water is coming out of the cold taps when mains is shut off the the valve is working.

Trace the pipework to the cold water tank (if you can) to see where it's being fed from...

 

[fjs]

I cannot trace the pipework. I do not understand how the downstairs toilet can be fed differently from the upstairs. I should not have used the word 'force'. I am not heavy-handed. The water meter ticks when there is a flow through it. I shall make sure it is silent before undertaking work. Got there for now. Thank you.

 

[JCSPLUMBING]

Most probably cistern fen from the tank in the loft. I've known baths to be cistern fee but basins not! If the gate valve is letting by then you will have to drain down your loft tank by turning off the main stopcock and opening the cold taps that it supplies. You would know this by water coming out of the ones even though it's turned off at the mains. It may take a while so get comfortable. Oh and when you change it, chuck an isolation valve on there ready for next time