If you find a leak in the evening and cannot stop it any other way, turning off the water at the stopcock overnight is often the safest option, as long as you can do it safely. If the leak is from a single tap, toilet or appliance, closing its isolating valve may stop the water without cutting off the whole property.
Either way, the aim is to stop water escaping while you wait for a repair.
Try the Isolating Valve First
Many toilets, taps and appliances have a small isolating valve on the supply pipe. These are often turned with a flat-head screwdriver or a small lever. If the leak is clearly from one fitting and it has a valve, closing that valve may stop the leak while leaving water available elsewhere in the home.
If you cannot tell where the water is coming from, or there is no isolating valve, the stopcock is usually the next step.
Turning Off the Stopcock
The stopcock is often under the kitchen sink, but it can be elsewhere. Turning it clockwise usually closes it. Once it is off, running a cold tap can show whether the supply has stopped.
If the stopcock is very stiff, do not force it. Old valves can be damaged, which may make things worse. A stopcock that will not turn is worth mentioning when you ask for help, and our stopcock repair page explains how faulty stopcocks are assessed.
Things to Think About Before You Turn It Off
It is also worth placing a bowl or towels under the leak and moving anything valuable out of the way, as some water may still drain from the pipework after the supply is off.
Turning off the mains overnight means there will be no running water from the mains until it is turned back on. You may want to fill a kettle and some bottles first. Some homes have stored water in tanks, so certain taps or toilets may keep running for a while after the stopcock is closed.
In the morning, turn the stopcock back on slowly and check the leak again before using taps and appliances as normal, unless a plumber has advised you otherwise.
If anyone in the home relies on water for medical reasons, or if you live in a building where the stopcock serves more than one property, consider this before isolating the supply.
When Turning It Off Is Not Enough
If water keeps escaping after the stopcock is closed, or the leak is near electrics, keep clear and seek help rather than waiting for the morning. For situations that may need plumbing help outside normal hours, it helps to describe what you have already tried.
If you have found a leak late in the day and are unsure whether to isolate the supply, a plumber can talk through the situation and explain the next step.