Need to turn water off for repair to hot water tap in bathroom (upstairs). Turning stop-cock (under sink downstairs)seems only to drain cold water off and will do this quickly. How do I drain said water/tap, hopefully not having to mess with external supply. Cheers in advance

Depends on source of hot water I guess. Mine is a combi boiler so turning off water under sink cuts off water to hot tap as well. If its coming from a hot water tank, therell be an isolating valve associated with that. Failing that, you could turn all water entry to the house off via the stopcock located outside the property (The one the water supplier would use).

turn stop cock off and then open the hot water tap downstairs. this will drain the hot water from the hot water tank and you can mend the tap. when done turn stop cock back on and let the hot water tank fill up again. turn your heating on to heat the water. put kettle on and have a brew happy in the knowledge of a job well done.

it may take a while for the water to drain down.

toppers3933 – cheers for that doing it now, see how long it takes to drain hot water… could be 5 or 35 mins to my knowledge?

depends how big the water tank is. open all available hot taps. its a tragic waste of hot water but short of freezing the pipes theres not really another way of doing it.
happ to help.

Also worth looking at the pipe leading to the hot tap, there is often a valve to isolate it. It will have a slot screw head, a quarter turn so the slot goes across the pipe will stop the flow and save draining the tank.
If I were staying long term and had the pipe drained, id fit one for next time.

Nonsense, you don’t need to drain the hot tank. That’s also very wasteful. The water comes out of the top! Isolate the cold feed to the hot tank. Then open all the hot taps in the house. Ten seconds later the dribble will stop and you’re done.

If you have no tap in the feed from the cold water header tank, (the plastic or galv steel one in your loft). You might be able to put a cork in the output which is at the bottom.

Have you checked to see whether there is an in-line isolator on the tap feed itself?

if everyone in the UK turned off their stop-cocks at once would the mains explode and water start gushing upwards into the streets?

Yes – find the stopcock on the pipe from the header tank to the cylinder. If not, look for an isolator on the pipe to the tap.

if everyone in the UK turned off their stop-cocks at once would the mains explode and water start gushing upwards into the streets?

very unlikely

this country is no fun. 👿

If you’ve got a hot water cylinder fed by a header tank, you’ve either got to isolate the feed from the header tank or turn off the mains water and drain the header. You might find that the only outlet from the header is the cylinder – in which case lots of hot water wasted. Or run a bath. Some houses used to have the cold water in the bathroom fed from that tank (mine does) so you can just run the bathroom cold tap till it stops.