Kingston Plumbing

Isolating the mains water supply

Customer service is our priority, and we want to help you save money, so we are here to offer you an affordable plumber in Hull. Sometimes, there is no need to pay for a plumber to fix issues you may have in your property.

Throughout the duration of this post, and other posts in this DIY section, you will learn how to prevent issues occurring to your plumbing systems, and fix minor issues you may have.


Stop Tap

Most domestic properties have 2 stop taps, an internal stop tap and an external stop tap. Locating them can sometimes be difficult, but usually; an internal stop tap is generally located under the sink in the kitchen, either in the cupboard, or under the kick board under the sink.

You must be aware of where your stop tap is for property incase of emergency, equally you should know where to turn your gas supply off and the same for electrical, knowing where the fuse board is.

The external stop tap is generally located in your front garden, or on the path by your boundary. It can sometimes even be in your neighbours garden! Search for it well, you will have one somewhere which isolates the main supply to your property. If you cannot locate your stop tap, contact your local water supplier (Yorkshire water in this area) and they can assist in locating this for you.


It is all being well knowing where to isolate the cold water supply for your home, but how do you turn it off? Turn the spindle clock-wise to close the tap, and to open – it’s anti-clockwise. If your stop tap is a struggle to turn clock-wise, turn it anti-clockwise and then reattempt to turn it clockwise to isolate the supply. You can use tools such as a spanner or a specialist stop tap key to aid turning the water off if it’s stuck or difficult to reach.

If the internal stop tap does not isolate, or you simply don’t have one, you will have to use the external stop tap in the street or your garden. Again, the use of the stop tap key will help reach the tap, as it can sometimes be too far down to reach, and even covered in a lot of dirt (very daunting to put your hand down there when you don’t know what you’re touching). Same applies to external stop taps as internal, turn the tap clockwise to isolate the supply and anticlockwise to open.


Header Tanks/Cisterns

Header tanks are not very common these days, but they still do exist! If you have an issue with your plumbing system, to turn the water off can be a little bit more difficult, as you may have to go up into the loft, to turn the water off. Now you’re going to need ladders…

First, turn off the mains supply to the property with the use of the internal or external stop taps. If that does not stop the water, you will have to isolate the feeds from the cistern.

If the problem exists on the hot pipe, locate your Hot Water Storage Cylinder (HWSC), there will be a (Usually red) gate valve above the cylinder on a pipe which runs from above (Into the loft) and goes into the bottom of the cylinder, if you can see that, turn the gate valve wheel head clockwise to isolate the supply to the cylinder and open all the hot taps around the property to drain the hot water quicker. You must isolate the electrical supply to the HWSC too, to prevent the immersion heater powering and burning out.


If the problem occurs on a gravity fed cold pipe (we know this by the pipework being cold, and water does not isolate when the mains stop tap is isolated), then you will find the gravity cold isolator in the loft. Go up into the loft and locate the header tank, you may have 2 header tanks. In that case, it will be the larger of the 2 (it will be substantially larger than the other). On the side of the cistern, you will again find a (again red) gate valve coming from the bottom of the cistern, usually on the opposite side to the cold mains fill valve. Turn the valve head clockwise to isolate the cold supply. Once done so, run the cold taps in the bathroom (running the cold tap in the kitchen sink is irrelevant as this will be mains fed).


Preventing Your Stop Tap Ceasing

Once a month you should turn off your internal stop tap to prevent is ceasing. The last thing you want when you have a leak is to not be able to isolate your mains. So to prevent your stop tap from leaking, the best way is to turn the internal stop tap spindle head anticlockwise to isolate the supply and turn it back clockwise. When you turn the stop tap back on, turn it all the way open, then turn it anticlockwise quarter of a turn. Turning it back quarter of a turn is for insurance, so if it ceases and you cant turn the spindle head clockwise, you’re able to turn it anticlockwise then back clockwise to open. If you didn’t have the ability to turn the spindle head anticlockwise and only clockwise movements were available, problems would occur if the tap ceased in the future. So ALWAYS remember to turn the stop tap back a quarter of a turn when turning the water back on!


Leaking Stop Tap

If your stop tap has a small drip from the spindle, it is a very easy, simple fix. The only tools you will need, is a small adjustable spanner, PTFE tape, a small slotted screwdriver, a small Phillips/PZ2 (cross headed) screwdriver and PATIENCE!

The reason why this leak has occurred is the packing gland has ruptured, usually due to hard water and limescale (very common around Hull and East Yorkshire), and to fix the leak, you must repack the gland, and it’s easy to do that yourself, saving you the cost of having a plumber to do this for you!


Firstly, you can grab your small adjustable spanner and try to nip up and tighten the packing nut further to see if the leak stops, if not, you must isolate the water, turn the stop tap off! Remove the head from the tap, to do this, use your Phillips/PZ2 screwdriver, undoing the screw anticlockwise and lifting off the head. Undo the packing nut with a small adjustable spanner, turning it anticlockwise. Try to hold against the stop tap to prevent the whole tap from spinning and moving as this can cause you further problems. Once the packing nut is off, use PTFE to wrap around the thread of the gland nut, approximately 8-10 turns should be enough. Ensure you wrap the PTFE tape against the thread, so anticlockwise (opposite way as to the thread goes into the tap).

Screw the gland nut back into the tap with just 1 turn, so it’s just being held there. Wrap more PTFE around the tap spindle, around 5 turns, again – anticlockwise. By using your slotted screwdriver, poke the PTFE tape down into the packing nut.

Tighten the gland nut with an adjustable spanner until tight, re-install the spindle head with the screw and Phillips head screwdriver and open the stop tap to allow water flow. If the leak persists, wrap more PTFE around the spindle and poke down again using the slotted screwdriver like before, continue this step until the drip stops.


Stop Tap Doesn’t Isolate Supply

If you try to turn your internal stop tap off to isolate the mains supply, and you’re finding that the water is still flowing through the tap, you will need to replace the rubber washer. When the spindle is turned clockwise, it moves  a rubber washer inside of the tap, onto a seating, creating a water tight seal. If the washer is damaged, the seating and washer will not sit correctly, not giving a water tight seal, so you will have to replace the washer.


Firstly, isolate the water supply externally using the external stop tap. Drain the water from the pipework by opening all the tap outlets around the home. Once the water has stopped running out of all the taps, close all the taps, leaving the kitchen sink hot and cold open. Grab a bucket or a large bowl to catch excess water which may come from the stop tap, using your adjustable spanner, undo the larger of the 2 nuts on the spindle, turning it anticlockwise, this is when you may get a bit of excess water from the pipework, It shouldn’t be too much to cause an issue (less than a litre or so…), don’t worry!

You should now have exposed the old tap washer, replace it with a like for like washer. Now reassemble the tap, ensure the nut is tight. Open the stop tap using the spindle head and open the external stop tap and test. Once water is coming from hot and hold outlets at the sink, you can shut them off. Test your repair by closing the stop tap and opening all the hot and cold outlets once again and ensure the flow eventually stops.


Kingston Plumbing are proud to supply Hull and Surrounding areas with your local affordable plumber, we pride ourselves on our premium workmanship and brilliant customer service.

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