I guess you have found us because you are trying to turn off the water for some reason, but you are having a problem. It’s not always a joy to have problems, but it can be very helpful to know what to do when they happen.

Well, you are not alone, this is a very common problem that I see an awful lot. Someone turns the stopcock off and the water is still running out of the taps. What could be the reason? Is this even possible?

We will have a look at the answers to these questions and more. Luckily, there are a few things you can do to fix this issue before calling for professional help!

What is a Stopcock?

A stopcock is a name given to the primary isolation valve that controls the flow of water into your home. Most homes will have 2 of these, one is usually located inside the home and the other is usually located at the end of the garden in the street under a drain cover marked ‘W’.

You are likely to find all sorts of isolation valves in your home, in fact, they are everywhere that you have any kind of pipe system and you may not even know it. There are isolation valves on everything from taps, radiators, and boilers to washing machines, icemakers and occasionally fridges.

How to Turn a Stopcock Off

There are a few different ways to turn off the stopcock and it all depends on where the valve is located and what type of valve you have.

The stopcock valve that is located inside your home will often look like a tap head but instead of a waterspout, it will be located in the middle of 2 lengths of pipe. In this instance, the tap head can be turned to open and close the stopcock.

Stopcocks that are located outside in the street come in various designs and for some older ones, you will need a special tool (amazon link – opens in a new tab) to enable you to shut it off.

Newer stopcocks are much easier to use and have a small handle that can be turned by hand.

Why is the Stopcock Off but the Water Still Running?

Okay, so you have turned the stopcock off and the water is still running. This should not actually be possible, so this indicates either one of two things…

1. Stopcock is Not Actually Turned Off

The first reason for there still being some water flow no matter how small is because the valve has not been fully turned off.

You need to be sure that it is definitely the stopcock that you are turning, and you can try and undo it a little and turn it off again with a little more force to see if that helps solve your problem, but if not, it leads us on to reason 2.

2. Faulty or Worn Stopcock

The second reason that you may have turned off the stopcock and there is still water flowing through the system is because the stopcock is actually seized, worn out or faulty.

It is not uncommon for a stopcock to become worn out and seized. Think about how many times that valve actually gets used throughout the year or even throughout a decade.

If you have found that your stopcock is faulty or damaged in any way, it is best to just replace it with a shiny new one.

How to Replace a Faulty Stopcock

Replacing a worn stopcock that is located inside your home is an easy task to carry out without calling in a plumber. If, however, it is the stopcock in the street that you are trying to shut off, this is the responsibility of the water board, and you should not attempt any maintenance on it at all.

What You Need

  • New Brass Stopcock Valve
  • Stopcock Valve Tool (depending on type)
  • Bucket
  • Towel/ Rag
  • 2 x Adjustable Spanners

Step 1 – Turn off the Mains Water

The first step is to isolate the whole house from the water supply. This means locating the main stopcock that is usually located in the street somewhere. These can sometimes be a bit of a pain to find as they can be well hidden.

Open the stopcock drain cover (marked ‘W’ or ‘Water’) and you will be able to turn the mains water off completely. If you are in an older property, you may need to buy an inexpensive tool to help you open and close the valve.

Note: Some properties share a stopcock that is in the street so you may need to check and let your neighbours know if you are turning the water off!

Step 2 – Undo the Union Nuts

Depending on where your stopcock is located, you will need to prepare your bucket or towels ready to catch any water that escapes – a little water is to be expected.

Now you can undo the nuts that are holding your stopcock tap in place. These are likely to be very stiff and you will need to have a good grip of the tap head whilst turning the nuts to prevent the tap from twisting and potentially causing more damage.

The stopcock nuts are almost all universal so the nuts and the olive can be left in place.

Step 3 – Swap Your Stopcock Over

Your stopcock valve will have an arrow on the side that needs to be aligned with water flow into the property. This is extremely important!

Swap in the new stopcock and if you are using the old nuts and olives, it is a good idea to use a little PTFE tape around the threads of the new stopcock.

If the old nuts and olives are no good, the olive may need to be cut away and you will need to use the new ones that come with the fitting.

Tighten up the union nuts and ensure that they are done up very well.

Step 4 – Turn the Water Back On

Now you can turn the water back on, but you will want to do so in a particular order. First, leave the newly replaced stopcock open and then open the kitchen taps.

Now turn on the water from the main stopcock outside and the water should begin to freely flow through the taps in the kitchen.

Now shut off the kitchen taps and then close the newly installed stopcock so you can check for leaks etc.

The reason that we turn the water on in this way is so that you are back inside the house and near to the stopcock when the stopcock is put under any pressure. There is nothing worse than coming back inside after turning the water on and the fitting is spurting water all over the place.

It should not happen if done correctly but it is always better to be safe than sorry.

How to Prevent Stopcock from Seizing

Stopcocks that are left untouched for long periods of time are likely to seize, particularly in hard water areas where there is a higher chance of scale build-up.

The best thing to do to keep a stopcock from seizing is to keep it moving. Every month, make a point of going to the stopcock and turn it off and then on again. This will keep all of the parts that move free of crud and in working order.

Conclusion

Is your stopcock off and the water is still running? Well, no. The stopcock isn’t actually off at all and there is a good chance that it needs replacing.

Stopcocks are easy to replace and can be done with little to no expertise so you should be able to crack on and do it yourself.

Plumbing Wizard Tips

“Remember to let your neighbours know that you’re turning the water off if you share a stopcock!”

“Turn your stopcock on and off once a month to keep it moving and free of build-up!”

“If your stopcock is not functioning correctly, replacing it is the easiest option, let the scrap man take away the old one!”

“If your main stopcock in the street is faulty and not working, call the water board – do not attempt to fix it yourself!”

Frequently Asked Questions

Why is my water still running after main shut off?

Water is still running after the mains have been shut off because the mains cannot have been shut off correctly. There are 2 primary reasons, one is that the valve has not been turned enough to close off the water supply; the other reason is that the valve is faulty and needs replacing.

How long does it take to drain water after shutting off Main?

Once the mains have been shut off, typically with one tap running, this could take around 30 seconds.

Why does my water valve not shut off?

In most cases water valves become seized which means that they will not shut off. This is very common especially with valves that have not been used for a long time and have a large build-up of scale and other minerals.

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