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You are here : At Home > My Water > Water quality > Appearance of your water

Appearance of your water

Any changes in the way your water looks can seem a bit worrying but in most cases there is a simple explanation and an easy way to put things right.


Watch our video for advice on dealing with discoloured or aerated water

Here are the most common changes you might notice:


  • White, cloudy or milky looking water

    Air in the water is the most common cause of white, cloudy or milky looking water.

    What can I do?

    There is an easy way to prove this is air:

    1. Fill a clear glass with water and watch carefully. You should see that the water will clear from the bottom upwards as the air lifts out of the water. The water should become completely clear with no sediment or discolouration.
    2. If the water does become clear, this is definitely aerated water. Air does not affect the quality of your water.

    The air generally clears by itself within one or two hours. If it goes on for longer or you are concerned please contact us and we can advise you further.

    What causes this to happen?

    Warm Water

    •  If water warms up in the pipework this will cause naturally dissolved air to come out of solution and cause cloudy water. If running the tap for a short time clears the cloudiness, it may be that you need to lag your hot or cold pipes to prevent this from happening.

    Tap Washer

    • A faulty tap washer can also draw air in and make the appearance cloudy. Check other taps in your property, if your taps are dripping or flow changes solve the problem. If so replace the washer with an approved product.


    • If the pressure in our water mains has changed, the disturbance can cause the water to become more aerated (bubbles of air can become trapped in the water) and this can make your water look really cloudy. This might happen after a burst or repair, when a fire hydrant has been used or if your stop tap has been operated recently. Check our incident alerts for on-going works in your area.

    Heating System/Boiler

    • If you notice cloudiness or air in your hot water but your cold water is clear, this suggests it may be a problem with your heating system or boiler. Unfortunately, we can’t help with this so you may wish to contact the manufacturer or a WaterSafe plumber or GasSafe heating engineer.
  • Brown or discoloured water

    All our water supply networks contain iron mains which over time slowly corrode producing a small amount of iron deposit. For the vast majority of time the water flows over these deposits without disturbing them. However, when the rate or direction of flow changes significantly e.g. if a main bursts or a fire hydrant is used, the deposit is picked up into the flow of water, giving the water a brown/yellow/discoloured appearance.

    What can I do?

    1. To flush through, you should run your cold kitchen tap or the first tap connected to the mains at a steady rate. This may take some time to clear and we suggest you try running it for 5 minutes at first.
    2. If the water begins to clear, you can continue until it clears completely. If it does not appear to improve, then please check our incident alerts for on-going works in your area at
    3. If it goes on for longer or you are concerned then please contact us and we can advise you further.

    Please note: If the problem is because of a burst or works on our network, we will always flush the water supply network to return the water quality to its normal high standard, but you may need to run your cold kitchen tap to clear any discoloured water that may have entered your supply pipe. Running your kitchen tap will not be effective if the problem is still happening, so you may need to wait.

    We also recommend:

    That you do not use appliances connected to the water supply, such as washing machines or dishwashers, until the water has cleared as it can also cause staining to your washing. If this has happened to your washing then don’t let the clothes dry out and wash the affected items in water containing a product specifically designed to remove rust stains.

    If the discolouration is due to the disturbance of the harmless layer of sediment, you may not wish to drink the water because it looks unpleasant and we advise that you do not use the water to make up babies' bottles.

    What can cause this?

    Service pipes

    • Another possible cause for discoloration is the internal corrosion of galvanised iron service pipes (the small diameter pipe that connects your property to a water main). This type of discoloration is sometimes apparent when water is left standing, particularly overnight, and will usually clear very quickly when you run your cold kitchen tap but will reoccur frequently. You may find that your neighbours are not experiencing the same issue and it would be advisable to contact a WaterSafe plumber who can advise you on the next steps to take.

    Storage tank

    For more further information about approved plumbers please check our website.

    • If you have brown deposits in your hot water, this may be caused by the deterioration of your storage tank. You may wish to contact a WaterSafe plumber or heating engineer who can advise you on the next steps to take.
  • Water seems to be blue

    Hot water tanks and most household pipes are made from copper. In very new buildings or buildings with new plumbing, small amounts of copper can dissolve into the water. Usually, this doesn't cause any problems other than the slight risk of staining, particularly on white baths and sinks. However, the water can sometimes develop a distinct blue tint if it has stood in contact with the pipes for a long time.

    What can I do?

    Usually this problem only lasts for a few days until a layer of limescale builds up on the inside of the pipes. If the problem has been happening for several weeks or months, we would advise you to contact either the company who built the property or carried out the renovations or an approved Water Safe Plumber. This is far more common if you have a water softener installed at your property which you should notify our Fittings Regulations team about.

    What can cause this?

    Block in toilet cisterns

    Another reason for blue water is due to the use of toilet blocks in cisterns. Inadequate backflow protection has been known to cause blue water at other taps within your property. If you notice this we recommend you contact a WaterSafe plumber to assist and let us know too.

  • Suspected staining caused by water

    From time to time you may notice stains or discolouration in the areas where you use water, e.g. around taps in sinks and basins. In nearly all cases this is not caused by the water itself. However, we can offer some easy solutions to help you resolve this problem.

    Pink or red stains

    The reddish-pink colour sometimes seen on shower curtains, bath sealant or around taps is not caused by the water itself but by the growth of common bacteria or yeasts. Both can thrive in moist, warm environments like those found in the bathroom. These bacteria or yeasts are naturally occurring and can be present on surfaces or air-borne, and their presence does not indicate a problem with the quality of the mains water supply.

    Black, grey or reddish staining

    This type of staining can occur around taps in the bathroom or showers, on the grout between tiles and in your washing machine powder drawer. The staining is caused by the presence of air-borne mould that can grow and spread in damp areas. The problem can be made worse if the area is poorly ventilated or if aerosol deodorants or other sprays are used. The aerosol droplets can provide a food source for the mould.

    What can I do?

    The best solution to both problems is to regularly wipe down wet surfaces and increase air circulation by opening a window or fitting an extractor fan to ensure that affected areas are quickly dried out after use.

    Household cleaners, disinfectant or bleach solution can be used to kill off the bacteria or yeast spores and clean off staining. There are also specific cleaners designed to tackle mould. Always ensure you read the instructions on any products you use. It can sometimes be more beneficial in preventing regrowth if household cleaners that do not have fragrances are used, as sometimes the fragrances can encourage more growth.

  • Orange/Pink particles

    Some customers may experience an orange slime like substance coming through taps. This is sometimes best described as frogspawn or jelly like in appearance and looks like small beads.

    What could cause this?

    The first thing to check is whether or not you have a water softener installed. If you do have a water softener in the property, this is almost certainly the cause. This happens when the softeners internal filter breaks, and can cause the substance to leak into the domestic plumbing system. It is also important that you have water softeners regularly serviced and maintained in accordance with the manufacturers guidance.


    If you do NOT have a water softener and are experiencing this then please contact us for further advice.

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