Water appearance

Discoloured Water

What causes discoloured water?
Discoloured water which can be yellow, orange, brown, or black is caused by particles of iron or manganese, which usually come from cast iron water mains and have settled over time in the network. A burst water main, high demand during hot and dry periods, or improvement works on our water mains will increase the water flow and can stir up the sediment. Discolouration doesn’t usually last more than 24 hours and the only way to clear it is to let it work its way through the system.

Although it doesn’t look nice, the levels of iron and manganese found in discoloured tap water are unlikely to be harmful to your health.

Sometimes discoloured water may be due to a problem with the pipes or plumbing inside your property. If your neighbours’ water is clear, and water from your kitchen cold tap is clear, discoloured water from any other taps is usually a sign of an issue inside your property. If this is the case, you should contact your plumber for advice. We recommend the use of plumbers listed on WaterSafe – the national register for qualified and competent installers. You can search for one here.

Useful tips

• Run your taps to help flush the water through. The majority of the time, flushing your taps between half an hour to an hour will help clear any discolouration.
• Don’t do any laundry as the discolouration may stain the washing. If this happens, wait until the water is clear and wash your clothes as normal.

If you still have discoloured water at your kitchen tap after running your tap, please contact us. We may need to come and flush the system to help it along its way.

Milky or White water

What causes white water?

Air in water
Milky or cloudy water is due to lots of air bubbles in the water, which are so small it makes the water appear white. The air bubbles are quite harmless and will quickly clear. But if it doesn’t clear, it could be that the mains water is affected and not just your property. This could be due to work in the area, such as fixing a burst main. You can check if any work has been carried out near your property in our In Your Area site.

Cloudy water normally clears from your water within 24 hours. If it’s coming from the mains, the only way to clear it is to let it work its way through the system.

Scale or white particles in water
A fine scale can develop because of natural minerals that occur in the water. Heating water, particularly boiling, releases these and if you live in a hard water area, they appear as white flaky ‘bits’ or particles known as limescale. The quality of the water we supply to you is not affected by air or scale. In fact, tap water always contains some dissolved air and without it, can have an unpleasantly flat or stale taste.

Sometimes milky or white water may be due to a problem with the pipes or plumbing inside your property. If your neighbours’ water is clear, and water from your kitchen cold tap is clear, any milky water from any other taps is usually a sign of an issue inside your property. If this is the case, you should contact your plumber for advice.

Useful tips
It’s really easy to see if your white water is due to air or hardness particles in the water:

• Fill a clean glass with cold tap water — if the bubbles clear from the bottom up, then it’s air.
• Run your taps to help flush the water through. The majority of the time, flushing your taps will help clear cloudy or white water.
• If you live in a hardwater area and after clearing there is a fine layer of particles at the bottom of the glass, its likely due to hardness. For more information on water hardness, please see the ‘In your Area’ section.

We recommend the use of plumbers listed on WaterSafe – the national register for qualified and competent installers. You can search for one here.

If you’ve had air in the water at your kitchen tap and it does not clear after running your tap, please contact us. We may need to come and flush the system to help it along its way.

Blue, pink, green or any other colour in water

Possible causes

Copper piping
Sometimes when water has been standing in copper pipes for a long time, copper can build up in the water and can cause it to look blue or green. This can also happen with new copper pipes but this should get better with time because a protective scale builds up on the inside of the pipes that stops the copper from being released. It may give your drinking water an unpleasant bitter taste or stain your sanitary fittings.

Coloured disinfectants in toilet cisterns
A faulty toilet cistern or poor plumbing could cause water to backflow from the toilet cistern to your taps. If you use a blue/purple/pink toilet cistern sanitiser (a loo block) and your toilet cistern is faulty, this would discolour the water coming from the taps. For more information or advice, please see our help page on WC compliance.

Useful tips

• Run your tap for a few minutes until the water clears before using it, especially for new copper piping installations. 
• If you have flushed your system and your water is still discoloured or the discolouration keeps coming back, please contact us. We may need to come and carry out some investigations to help find out what is causing the problem.

For further advice on blue, pink, green or any other colour discolouration, you should contact your plumber for advice as it may be due to an internal plumbing issue.

We recommend the use of plumbers listed on WaterSafe – the national register for qualified and competent installers. You can search for one here.

Bits in your water

Causes
Occasionally, some customers may have yellow, orange, brown or black particles in their water which can cause the tap water to become discoloured. This is caused by particles of iron or manganese, which usually come from cast iron water mains and have settled over time in the network. A burst water main, high demand during hot and dry periods, or improvement works on our water mains will increase the water flow and can stir up the sediment. Discolouration doesn’t usually last more than 24 hours and the only way to clear it is to let it work its way through the system.

Black slime (biofilms) can cause black particles in your water if they are building up on a tap or shower head. These are harmless and the only way to prevent them is to regularly clean the area they are growing on with a mild bleach or sterilizing solution such as Milton. The growth of black slime is a private internal plumbing issue and not an issue with the mains water supply. See our page on Slime and Staining for more advice.

If you are experiencing white particles in the water, this may be due to either water hardness or an issue with your internal plumbing system.

Some particles may be caused by lead pipes that are in poor condition. For more information on lead pipes, please see the Lead Pipes section in Water Quality In Your Home.

Galvanised supply pipes can also cause particles in drinking water as they can corrode over time. If you have particles in your water supply and are aware of galvanised pipes at your property, you should contact your plumber for advice.

Some customers may have black particles in their water. This can be caused by old alkathene supply pipes which can deteriorate over time potentially causing water leaks and low pressure. If this is the case, you should contact your plumber for advice.

Useful tips:

• Run your taps to help flush the water through.
• If you have yellow, orange or brown particles in your water, don’t do any laundry as the discolouration may stain the washing. If this happens, wait until the water is clear and wash your clothes as normal.

We recommend the use of plumbers listed on WaterSafe – the national register for qualified and competent installers. You can search for one here.

If you still have particles in your water at your kitchen tap after running your tap, please contact us. We may need to come and flush the system to help it along its way.