Tracking Down Your Water Pressure Problem

To help you track down the problem and manage your water pressure, we have provided examples of some of the most common types of problems below:

After flowing through our mains to your underground supply pipe, the water goes to your combination boiler. The boiler then supplies all the hot taps inside your home. Combination boilers will not work below certain pressure levels. While conventional boilers will run on as little as 0.5 bar, combination boilers generally need more for them to function effectively. The pressure your boiler needs may be above the target we aim to supply in our mains, which is 1 bar as measured at the boundary of your property. If your plumber has assessed your water pressure to be below 1 bar, it is likely that this is due to the condition of your pipework. It may also be the case that some combination boilers are capable of supplying only one hot tap with water at any one time. Also, the pressure at your cold-water taps may reduce if they are run at the same time as a hot tap.

If you are planning to install a new boiler soon, please make sure that you or your appointed plumber check that your chosen system will work efficiently at our target water pressure of 1 bar. We aim to meet this target at the boundary to your property. Any reduction in this pressure will be due to plumbing issues on your water pipes. Please remember that water pressure is not constant and that demand, especially during busy morning and evening periods, will reduce water pressure in the mains network.

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Water from our mains goes to your kitchen tap after flowing through your underground supply pipe. Water then goes to a storage tank in your loft, and this tank supplies all the other taps in your home as well as your hot-water system. The height of the tank above your supply pipe will affect how quickly it will refill (pressure is lost the higher water has to be lifted). The height of the tank above your other taps will affect the pressure at which water is fed to those taps. You will need to check if you have this plumbing arrangement.

A diagram of a system supplied by a tank

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For some customers, the problem is caused by sharing a supply pipe from the water main. This can be a problem if the supply pipe is too small, in poor condition (for example, leaking or old), or if customers sharing a supply use water at the same time. It can also be particularly noticeable at busy times when many customers sharing a supply pipe are placing demands on the water supply. So, a supply that seems fine at some times of the day may not be at other times.

If you and your neighbours share a supply pipe, you are jointly responsible for it from your property to our stop tap.

The houses in the example below have a shared supply pipe and a joint responsibility for maintaining and repairing it. If you have reduced water pressure and you are on a shared supply pipe, talk to your neighbours to see if they are experiencing the same problem. If so, you may want to call your local plumber to investigate whether a separate independent service pipe can be installed from your property to the main.

Please note that we would make an extra charge to connect the new pipe to the water main.

Diagram showing a supply pipe shared between several customer properties

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Flow and pressure in your home will be affected by the length of the supply pipe. On longer supply pipes, particularly those with a smaller internal diameter, we may be providing our target water pressure at the boundary, but the pipe may be too small to deliver the flow of water to your property that you want. This will appear to you as poor pressure, but is in fact caused by a small diameter pipe not meeting your demand for water.

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Some pressure problems can be caused by faulty, damaged or leaking pipes and fittings, for example, ball valves and stop taps inside your home.

Corrosion
If the pipes in your home are old, they may have become corroded, restricting the water flow. You may want to ask your local plumber to check this for you.

Stop Tap
A partly closed stop tap inside your home could be the cause of some water-pressure problems. Gently opening up the tap may increase the pressure. To fully open the tap, you should open and close it several times until the number of turns from open to closed is constant. Do not leave the tap fully open. Turn it back a quarter of a turn to stop it seizing up.

Leaks
Leaks from pipes or fittings will reduce the water pressure. If you have a water meter, check for a leak by taking a reading from your meter just before going to bed and again in the morning before you have used any water. If the figures are different, you may have a leak. If you do not have a meter, listen for hissing sounds from inside pipes or look for damp patches or very obvious green patches on your grass. If you suspect you have a leak inside your home, contact your plumber for advice. If you see a leak on your outside water pipes, contact us first.

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Pressure will be affected by the height of a property in relation to the local area around it. If your home is at the top of a hill, you may receive lower pressure than properties that are at the bottom of the hill, especially during busy times of the day such as morning and early evening and during the summer. We will always aim to supply a water pressure of 1 bar at the boundary to your property. However, if you feel this does not meet your needs, get advice from a plumber on improvements to your pipework. Your plumber may want to consider installing a water accumulator. This is a relatively new device that holds water in a vessel during those periods when demand for water in your house is low and releases that water as you need it at busy times.

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In the introduction to this section we explained that the plumbing layout in your home may affect the pressure at which water is supplied to your taps. It may also affect your shower. Many new showers will need a minimum level of flow and pressure to work effectively. Some will need to be supplied directly from the mains (not from a tank in the loft). In older showers, limescale may build up and cause poor flow at the showerhead. Always clean your showerhead every three months to prevent limescale building up. If you cannot remove the limescale, try replacing the showerhead and the hose attached to it with new ones.

If you are planning to fit a new shower or heating system soon, please make sure you check with the designer, contract installer or your appointed plumber to confirm that your planned system can work efficiently at our target water pressure of 1 bar. Any reduction to this pressure is likely to be due to plumbing problems with your water pipes. Remember that water pressure is not constant. Pressure in the mains system may be reduced due to busy morning and evening periods where the demand is high.

If you are planning to carry out some plumbing work in your home, it is always a good idea to check that the stop tap inside your home is working properly. In many homes, the stop tap can be found in the kitchen, near the sink.

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Sometimes, the installing of new appliances in your home can affect your water pressure. Similarly, someone may have used the stop tap outside your property and left it partially closed. If you have a shared supply pipe, you may not be aware that the stop tap has been used so check with your neighbours. If you have reason to believe that someone has used the stop tap, you should ask them to gently adjust it back to its original setting.

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What to do if you continue to have a problem