Once you’ve twisted it off, go turn on a tap—any tap—and see if water still flows. If nothing comes out, you’ve done it. You are now a hero of household hydraulics. If water still trickles, you might have turned the wrong valve, or your stopcock is older than your grandmother’s secret cookie recipe. In that case, try turning it the other way (counter-clockwise) just to be sure—some weirdos install them backwards.
And here’s a harsh truth: not every home has a fully functional stopcock. Some are hidden behind drywall, painted over by a landlord who believed in “modern art,” or simply rusted into a permanent “on” position. If that’s you, keep a medium-sized bucket and a sense of humor handy at all times.
A quick story, because why not?
I once tried to turn off the stopcock during a burst pipe at 2 AM. I had a flashlight in my teeth, and my cat was sitting on my head because he sensed I was panicking. I turned the valve, heard a clunk, and—nothing changed. Water kept spraying. Turns out I had twisted the gas valve for the stove instead. Classic move. Always double-check you’re spinning the right thing, or you’ll end up with a wet kitchen and a very confused oven.