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Water quality in England and Wales is regulated by the Drinking Water Inspectorate (DWI). They make sure all water companies supply safe drinking water that meets legal standards and is acceptable to consumers. The DWI produce detailed reports, sharing every water company's sample results and the conclusions of any audits or assessments. These reports, and other information on drinking water quality, are available on the DWI's website.

Our water quality monitoring involves sampling water in homes and businesses throughout the year. If we visit your property to take a sample and it's ok, you won't hear from us. The results will be assessed by the DWI and added to our postcode checker data, you can find water information about the water quality in your area here.

If your tap water looks bubbly, cloudy or white

Cloudy water is caused by tiny air bubbles in the water which make it appear white. They're not harmful and quickly clear, rising from the bottom of the glass upwards.

Depending on the length of time you have been affected, the cause will be one of the following things.

If the cloudy water has been present for a few hours, it may be caused by something that has happened on our network. We may have been working on your water mains network, perhaps fixing a burst main, and a pocket of air has become trapped and dissolved into the water. If this is the reason, it's normally short-lived and shouldn't last more than 24 hours. You can try running the taps for 30 minutes - if you do this, collect the water and use it for watering your houseplants or in your garden.

If the cloudy water has been present for a few days, we may need to flush the water mains to help it along its way. Give us a call and we'll endeavour to fix the problem.

If the cloudy water has been present for a few weeks or months, it may be caused by something inside your property. You can check the following:

  • Lag your pipes to prevent cold water being warmed by hot pipes.
  • If there's cloudy water from all taps, ensure your internal and external stop taps are both fully open.
  • If only one tap's affected, check your isolation valve under the sink is fully open.
  • If you still have trouble fixing the problem, get some advice from an Approved Plumber.

If you run your tap to help clear the cloudy water, don’t waste it, collect the water and use it to water your plants or wash your car.

If your tap water looks black, brown, orange, red or yellow in colour

IWNL's networks are comparatively new and therefore, the risks of receiving discoloured water are very low. However, on rare occasions your drinking water may still become discoloured or appear cloudy. This discolouration can range from a light straw yellow to a dark brown colour.

Why discolouration happens

A sudden change in direction or flow rate of the water in the network can cause the disturbance and re-suspension of the deposits. The resulting discolouration can range from a straw colour to dark brown.

Sudden changes in flow can be caused by a burst main or by a sudden change in demand for water, for example when firefighters tackle a large blaze.

The sudden appearance of discoloured drinking water is usually associated with the disturbance of the listed minerals depositing into the water pipes.

How to solve discolouration

Discolouration is usually solved by flushing the deposits from the water distribution system. This is achieved either by customers running their taps for an extended period or by Independent Water Networks flushing the discoloured water from the network using hydrant standpipes.

Some drinking water will contain the following metals. Over time these can deposit into the distribution system.

  • Aluminium
  • Iron
  • Manganese

How to solve discolouration

If your water looks different to the descriptions above, give us a call on 02920 028 711 and we will investigate for you.

How hard is my drinking water?

Some of the water supplied by IWNL is hard or very hard. This is because the ground rock has a high chalk (calcium carbonate) content. As water moves through these rocks it dissolves some of the chalk and this makes the water hard.

You can see how hard your water is by looking at the map below or by using our postcode checker here.

UK Hard Water Map

UK Hard Water Map

Hard water is perfectly safe and there’s lots of evidence it can even be good for you.

For more information on hard water, how it affects you and what you can do about it, please view IWNL’s flyer.

If you notice black, orange or grey 'bits', stains or slime

White or Grey Flakes or Particles

These are likely to be limescale if you live in a hard water area (see above). Although unsightly, these are not harmful.

These particles can also occur when a limescale inhibitor or a descaler fails. A plumber can check if your limescale inhibitor is working properly and you can find a list of approved plumbers in your local area.

Hard Black Particles

If you’re using a filter jug you may have noticed bits in the water, either above or below the filter section. These are likely to be the filter media from the filter cartridge. To prevent this happening:

  • Ensure the supply is particle free by visually checking the water from the mains fed tap.
  • Change the cartridges regularly and speak to the manufacturer if you continue to have a problem.

Orange Beads

If you have bits in your tap water that look like beads or sugar crystals or it tastes salty, this may be caused by a water softener that isn't working properly.

Check under your sink for any appliances plumbed in.

  • A plumber can check if your softener is working properly and that you have a non-softened tap available for drinking and cooking. You can find an approved plumber here.
  • Keep your softener well maintained and serviced regularly.
  • If you haven't got a water softener, but are noticing any of the problems described above please call us.

Black or Orange Stains/Slime

Why do these occur?

Fungal spores and bacteria are naturally present in the environment. Fungi like to grow in warm, damp, humid conditions and thrive where there is an additional source of nutrients.

These growths are known as biofilms or 'microbial slime'. When they occur they are most noticeable in bathrooms and kitchens. These growths can occur in various colours such as black, red and pink. If not dealt with at their onset some biofilms can grow into certain materials and leave a permanent stain.

Kitchens and bathrooms are generally the warmest and most humid rooms in the house. They also provide an environment that has numerous rich sources of nutrients such as propellants from aerosols (deodorants and hairspray), waste food and left over soap! These sources of nutrients can promote and accelerate the growth of fungal colonies.

What can I do to prevent growth?

One of the best ways to prevent fungal growth is to improve ventilation by using extractor fans and if necessary slightly opening a window to allow damp areas in kitchens and bathrooms to dry rapidly.

It is also important to eliminate the food sources for the fungi and bacteria to prevent growth, therefore keeping these areas clean and free from potential food sources will limit growth.

Where do they occur?

They can be commonly found in the following locations:

  • On shower curtains or towels – particularly around the bottom
  • On the end of cold water taps, kitchen bathroom or outside - particularly if they are leaking
  • In washing machines - particularly around the powder drawer
  • In toilet cisterns and bowls
  • On or in shower heads
  • Around bathrooms shower rooms – particularly on the grout or sealant strips
  • In refrigerator drip trays
  • In waste traps and overflows connected to sinks
  • In dehumidifiers

If you notice a chlorine or chemical taste or smell to your water

Chlorine and Disinfectant Tastes and Smells

Why can I taste TCP?

This problem can occur when the plastic or rubber parts in appliances or fittings start to react with the low levels of chlorine in the water.

These plastic and rubber fittings are not installed in the IWNL network but are commonly found around the house and workplace, for example in:

  • Kettles (plastic and metal)
  • Pipes and flexible hoses connected to drinks machines, dishwashers and washing machines
  • Tap washers

How to find the cause...

Is the taste in hot drinks only?

If this is the case then a part of the kettle may be reacting with the chlorine in the water to produce the TCP taste.

All types of kettles contain plastic and rubber parts that can cause this type of problem. To eliminate the kettle as a source of the taste, try boiling water in a clean metal saucepan. If the taste is no longer present then the kettle gasket that provides the seal between the heating element and the wall of the kettle is the most likely cause.

This problem may ease and eventually disappear as the kettle gets older. However, if it persists, then you may want to contact the kettle manufacturer for further advice.

Hose connections to appliances

Flexible hoses that feed water to domestic appliances such as washing machines or dishwashers can deteriorate over time and release traces of chemicals that can cause 'chemical' type tastes and odours that are particularly noticeable with hot drinks.

When an appliance is not in use, try isolating it. This can be done by using the valve that is installed on the cold water line at the back of the appliance. If this solves the problem we would suggest that:

  • Where the hose connects to the cold water supply install a non-return valve.
  • If a non-return valve is already installed it may be faulty and need replacing.
Taps and plumbing

If you notice the TCP taste or odour only occurs at one of your mains fed taps then this would suggest a problem with that particular tap. The most common cause of this problem is the washer in the tap.

This can be checked by running the tap for a short period to see if this improves the taste or odour. If it does, IWNL recommend that the washer is changed to a non phenolic or synthetic one.

For more advice on approved plumbing fittings please visit the Water Regs UK website.

It is worth noting that internal stop taps are also fitted with washers and that TCP tastes can occur when the internal stop tap has been operated to carry out any work or if the tap has been used for the first time in many years.

For further information on chlorine.

If your water has an unpleasant taste or odour it may be a good idea to check with a neighbour to see if they are experiencing the same taste and odour issues. If they are not then the problem is unlikely to be with the water supplied from the IWNL network.

Contact us...

If you are concerned about the quality of your drinking water, supplied to you by IWNL, please contact us on 02920 028 711.

If you notice an earthy, stale or fuel taste or smell

Earthy, Musty or Stale Tastes and Smells

These tastes and smells are often more noticeable first thing in the morning or when the property has been left for a period of time. Often the problem is coming from the waste trap in the sink rather than the water itself. Running the tap can disturb waste in the waste trap or u-bend. Try cleaning the sink trap and drain to solve the problem or run you tap for a few minutes. If you run your tap, collect the water and use it to water your plants or wash your car.

If this doesn't work, it may be that there is low turnover of the water in the mains and we may need to flush the main to clear any water that is not being used promptly. Please contact us so that we can investigate.

For further information on musty or stale tastes and odours.

Diesel, Petrol or Metallic Tastes and Smells

Diesel and Petrol

You should contact IWNL immediately if you find that your water tastes or smells of diesel or petrol.

This taste or odour may be due to a fuel spill close to your home. The chemical compounds in diesel and petrol can penetrate the plastic pipes used to deliver water to your home. Therefore, please clean up any fuel spills that occur on your property.

For further information on diesel and petrol tastes and odours.

If your water tastes or smells of diesel or petrol, please contact us on 02920 028 711.


If water is allowed to stand in taps, plumbing or other appliances for long periods of time, metals from the pipework or appliances can leach into the water.

Elevated levels of metals in water can cause some unusual tastes, odours and in some extreme cases, colour changes. Flushing of your pipework can quickly resolve these issues.

You should also check that your cold water pipes are not too close to your hot water pipes and getting warm as this may make the problem worse. If you do find that the pipes are too close and getting warm, then we would recommend that you lag these pipes.

For further information on metallic tastes and odours.

A useful guide from the water industry

Looking After Water in you Home

You can find a simple guide of household tips to help you enjoy the quality of tap water once it reaches your home. It also answers questions relating to water and hygiene issues in the home.