Water pipe in-line isolating valve.

Assuming you aren't talking about one of those little quarter-turn valves used to isolate a tap or washing machine etc., then the answer is clockwise when viewed from above.

If you are upside down, with your head inside a cupboard, stretching to reach the valve with your fingertips - it can be harder to work this out.

Thanks! :-)

And if it's not one of those quarter-turn valves (this one is isolating a shower) would it still be clockwise to turn it off?

It's not been used in the thirteen years I've been here and I really don't want to break anything by forcing it the wrong way.

Cheers,

Nick

There are two sorts of valves in genera uses. 'Gate valves which are like ordinary taps - screw down to shut. Clockwise.

And there are ball valves, which require a quarter turn in either direction.

open a tap in whatever it's feeding (or flush the toilet) and move it till the water noise stops

Thanks!

N.