The appearance of your water

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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 or milky looking water. There is an easy way to prove this is air:

  • 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.

  • If the water does become clear, this is definitely aerated water. Air does not affect the quality of your water and will generally clear over time.

There are a couple of common causes of this. 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.

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 at

The milky aeration generally clears by itself within one or two hours, although we may advise you to run your cold tap. If it goes on for longer or you are concerned please contact us and we can advise you further.

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

Some of the water supply system is still made up of iron pipes. Over the years the pipes can become rusty causing a harmless layer of sediment to build up in the pipes. A change in pressure, direction or the rate of the flow of water on the mains can disturb the sediment and it can be carried along in the water making it look brown or discoloured. Changes in the water flow can happen after a burst pipe, after sudden low pressure, if a fire hydrant is used (whether by the Fire Brigade or other third party), or when neighbours or contractors working nearby have used a shared stop tap or are working on shared supply pipes.

If the discolouration is due to mains deposits, these are mostly iron and sometimes manganese. You may not wish to drink the water because it looks unpleasant. It can also cause staining to washing. If this has happened to you don’t let the clothes dry out and wash the affected items in water containing a product specifically designed to remove rust stains.

Another possible cause for discoloration is the internal corrosion of galvanised iron service pipes (the small diameter pipe that connects your property to a main). This type of discoloration is sometimes apparent when water is left standing and will usually clear very quickly, but will reoccur frequently.

You should not use the water to make up babies' bottles and we would advise you not to use appliances connected to the water supply, such as washing machines or dishwashers, until the water has cleared.

If you have brown deposits in your hot water you may wish to contact a WaterSafe plumber or heating engineer. Brown water may also be caused by the deterioration of your storage tank or the condition of the service pipe connecting your house to the water main in the street. If this is the case your neighbours may not be experiencing the same issues. You may wish to contact a WaterSafe plumber who can advise you on the next steps to take.

What can you do?

If the problem is because of a burst or works on our network we will usually flush the mains but you will need to run the tap to clear the discoloured water from your supply pipe. The particles in the water will need to be flushed through or allowed to settle out. This won't be effective if the problem is still happening, so you may need to wait. 

To flush through, you should run your cold kitchen tap or the first tap connected to the mains. This may take some time to clear and we suggest you try running it for 5-10 minutes at first. If the water begins to clear, you can continue until it clears completely. It’s important when doing this that you run the cold mains fed tap on full pressure, to ensure the water clears as quick as possible.

If it does not seem to improve, you can check our website for scheduled work or emergencies in your area here (link to the Customer Zone page). If you are still concerned, you can contact us by telephone and we can give you further advice.

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.

Usually this problem only lasts for a few days until a layer of limescale builds up on the inside of the pipes. Obviously, if this has not happened in your case and 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 a 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.

A more recent issue is due the use of toilet blocks in cisterns. Inadequate backflow protection has been known to cause blue water at other taps within your property (see the WRAS video below to find out more). 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 to 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 slime

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. 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 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.