Water Quality FAQs

Advice on water quality problems, including cloudy or discoloured water, unpleasant taste or odour, Legionnaires' disease, and concerns about lead in your water supply. Also includes information on preventing illness caused by improperly fitted and maintained hosepipes and films with more information.


Why is my water discoloured?

On rare occasions tap water may become discoloured, appear cloudy, or appear to have very small particles in it.

Discolouration can range from a light straw yellow colour to dark brown. It can be caused by a number of things including:

  • Naturally occurring substances
  • Disturbance of mains deposits
  • Corrosion of service pipes
  • Internal plumbing issues.

In most cases discoloured water is not harmful and can be cleared by running the first incoming cold water tap (usually in the kitchen) at a trickle until it clears.

Very occasionally water suppliers receive calls about "tiny particles" or "bits" in their tap water. This can be caused by:

  • Planned or unplanned work to the water supply network which causes sediment in the pipes to shift (quite often this is a dark red, brown colour)
  • Small dark grey or black particles can occasionally be caused if your pipework is made from lead. This is most likely if your house was built before 1970.

For more information, please contact your  water supplier.

Please note: If your water is blue, pink, green or any other colour not described above, please do not drink the water or use it for cooking purposes until you have sought advice from your water supplier.

Why is my water blue/green?

Blue or green looking water is often due to the presence of new copper pipework, either in new houses or where new pipework has been installed in older properties. This is because these new copper pipes are settling in.

To help prevent this from happening, take the following steps:

  • Only use lead-free flux 
  • Flush through new pipework thorougly
  • Drain down plumbing systems which are not used immediately after installation.

Blue water can also be caused by poorly installed toilet cisterns, which allow water from the cisterns to siphon back into the internal plumbing.

For information about how to check your toilet cistern please visit the  WRAS website.

If your water is blue please do not drink the water or use it for cooking until you have sought advice from your water supplier.

Why is my water cloudy or milky?

Sometimes water can look milky or cloudy because it contains tiny bubbles of air. Air is always in water, but it can be more obvious after it has travelled through the mains, if there is a burst mains pipe or if a faulty plumbing fitting has been used.

As well as the change in how it looks, you may also notice knocking or banging noises coming from the internal plumbing.

To check if this is the problem, run a glass of water and allow it to stand for a few moments - the cloudiness should clear from bottom to top. To help fix this, you can try running the cold water tap at the first point of entry in to the property (closest to the internal stop tap) on a slow steady flow. While the tap is running, turn the internal stop tap on/off 4-6 times to help release the air from the pipes.

Cloudy water caused by tiny air bubbles in the water is not harmful to health.

If you've tried this but are still concerned, or you'd like more advice you should contact  your water supplier.

How can I improve the appearance of my water?

In this video from Wessex Water, you can learn more about issues with the appearance of your water, as well as tips for how to improve it.

Taste and Odour

Watch our short advice films on common taste and smell issues

Unusual drinking water tastes and odours can pose a significant concern for homeowners and businesses, but there are a number of ways to remedy these problems. Chlorine, antiseptic or TCP, earthy and musty, stagnant or sewage, and metallic or bitter tastes and smells are all common complains that can be resolved by following some simple guidelines or enlisting the support of a WaterSafe approved plumber. In these films, we feature advice from water quality experts, plumbers and the Drinking Water Inspectorate on the causes of taste and smells in tap water -- and how to avoid them.

Why does my water smell/taste of chlorine?

Chlorine in drinking water is not harmful, but some people are more sensitive to the taste and smell of chlorine than others. Chlorine is essential to protect public health and so it is added to drinking water as the final stage of treatment to kill any harmful germs that may be present. The concentration of chlorine in drinking water is monitored closely 24 hours a day.

Water suppliers try and keep chlorine levels as low as possible, while at the same time ensuring supplies are kept safe. Chlorine concentrations can vary throughout the day and through seasons, and may be higher if you live close to a water treatment works.

The taste of chlorine can be reduced by filling a jug or glass container, covering it and allowing the water to stand in the fridge until it is needed. If you don’t use it within 24 hours, you should discard it. If you do need to discard it then why not use it to water your plants rather than pouring it down the sink?

If you're really sensitive to the smell and can still detect it after storing it in the fridge, try boiling the water for about five minutes. This removes most of the chlorine. After the water cools, store it in a closed container in the fridge. Again, if you haven’t used it all within 24 hours please discard it.

You might also consider using a home treatment device like a water filter, generally these are not necessary but some customers like to use them. There are several types of water filters on the market ranging from jug type filters to permanently fitted devices. You will need a filter containing activated carbon, which absorbs chlorine and other substances which can influence the taste of the water.

Any device which is ‘plumbed-in’ must comply with the Water Fittings Regulations and Byelaws. If not properly maintained, these devices may cause problems with water quality.  Click here for further information and advice about the Water Fittings Regulations and Byelaws.

Sometimes chlorine reacts with materials used for tap washers, anti-splash devices and seals in kettles and this can cause an unpleasant ‘chemical’ taste.

A chlorinous or metallic taste in hot drinks, especially tea, will not be due to the presence of chlorine. Instead it is most likely to be associated with plumbing materials, such as rubber washers, or if you have appliances (such as vending machines, dishwashers or washing machines) plumbed in close to taps used for drinking water.

To solve this, either change the hoses for ones approved by  WRAS (Water Regulations Advisory Scheme), for example a food-quality hose, or change the isolating valve for one fitted with a check valve - also known as a one-way or non-return valve.

Why does my water smell/taste earthy or musty?

Water that passes through peaty land can have an earthy or musty taste and/or odour. The water treatment works in such areas are designed to remove the organic material that causes these tastes.

Several types of bacteria and algae that are normally present in lakes, reservoirs and rivers can naturally produce substances which are not harmful to health, but which can give a musty or earthy taste or odour to water. Some of these organisms can also grow on washers and the inside of taps in homes, which can lead to musty or earthy tastes or odours.

If you notice a smell or taste like this for the first time, try using a mild household disinfectant to wash outside and inside your drinking water tap. Don’t forget to let it run a little before you use it again to rinse out the disinfectant.


Why does my water smell/taste of rubber, plastic, antiseptic or TCP?

Some plumbing materials that come into contact with the water supply in homes, offices and factories can give water unpleasant tastes and odours. 

When water stays in contact with plastic or rubber pipes or fittings, small amounts of substances may dissolve into the water. Traces of chemicals routinely used in the manufacture of flexible plastic hoses, usually ones which supply cold water to dishwashers or washing machines, can interact with chlorine to create an antiseptic or TCP-type taste. When the drinking water tap is turned on a small amount of the water lying in these hoses can be drawn back into the cold supply. This problem usually occurs when the hose is connected directly to the rising main.

To check whether these hoses are causing the taste, close the isolating valve for 24 hours and then check the taste again.

You could also change the hoses for those approved by  WRAS (Water Regulations Advisory Scheme), for example a food-quality hose, or change the isolating valve for one fitted with a check valve.

This type of taste can also be caused by a having a garden hose permanently connected to an outside tap.

You should remove hoses from the tap when they are not in use and install a double check valve between the tap and the hose. A qualified plumber will be able to offer advice on how to do this.

As with all fixtures and fittings, plumbing materials deteriorate over time. Very old washers can begin to disintegrate or become damaged, for example by a worn tap seating, and this can change the taste of your water. The most commonly affected areas are the kitchen tap and the stop tap.

Try replacing old and worn out washers and or tap seats - this will help improve the taste.

Drinking water with this taste, although unpleasant, is not harmful in itself.


Why does my water smell/taste of antiseptic/TCP after being boiled?

Sometimes taste problems can arise after water has been boiled. As a general rule, if your drinking water is satisfactory prior to boiling and you then notice a taste after boiling the cause of the problem is usually the kettle. 

Boiling water in a saucepan on your hob or stove will help determine if your kettle is the cause of the unusual taste.

If you have a new kettle, allow a layer of limescale to build up inside it by boiling and then discarding the water a few times. Only boil the required amount of water each time. Do not re-boil water, rather discard it, rinse the kettle and fill with fresh water. Also try to avoid frequent de-scaling of the kettle.


Why does my water smell/taste metallic or bitter?

Higher levels of metals can be introduced into water through your internal pipework and can cause a metallic or bitter taste. 

This is most apparent after water has been standing in pipework for a period of time, such as overnight. You may also notice it in places where there are long runs of pipework or in places where water becomes warm as it passes to a drinking water point.

Try running water through the tap to clear any which has been allowed to stand. If you collect this in a bowl it can be used for watering plants rather than being wasted.

If you have new pipework the taste should improve with time as a thin protective layer of limescale will form on the inside of the pipework. Where water heats up during transit you should check the route of the pipework and the proximity of cold and hot water pipes. Affected pipework should be lagged or re-routed as necessary.

Occasionally glasses or cups that have been through a dishwasher may retain traces of detergents.

As a test, try rinsing the glass or cup with tap water and see whether the taste is still there. If so, adjust the settings on your dishwasher and use no more than the recommended amount of detergent and rinse aid.


Why does my water smell/taste of petrol, diesel or oil?

If there is a petrol or diesel taste and/or odour to the water from your kitchen tap please contact your water supplier straight away. Please do not drink the water or use it for cooking until you have sought advice.

Please check if you have had any work done at the property (for example on the heating system), if you have any oil fired heating/storage tanks on the premises or if you have recently had any oil leaks, i.e. a car or motorbike leaking oil. This is the most common cause for this type of issue.

Why does my water smell stagnant or like sewage?

Sometimes a sewage or stagnant-type odour can come from a sink/plug hole. This usually means there has been a blockage or build up of waste materials, which makes the drinking water appear to smell. 

Filling a glass with water and smelling it in a different room, away from the kitchen sink, will help you work out whether the odour is genuinely from the water or not. If you think it is the water please contact your water supplier immediately.

If the odour disappears when you're away from the sink you should try cleaning your sink/plug hole with a normal domestic cleaner. However, if there has been recent work on your service pipe, or you have had a new connection to your property, it could indicate a problem with this work and you should contact your water supplier immediately.

Lead in Water

Why should I check for lead in my water?

Lead is a dangerous metal which can cause serious poisoning if it builds up in the body. Babies and young children are most at risk as their development can be affected.

If the water supply to a home or business passes through lead pipes, or someone has used illegal lead solder to join pipes, the lead can dissolve into the drinking water.

The plumbing in your property is the responsibility of the homeowner, so it’s up to you to safeguard your health by replacing lead pipes with ones made of copper or plastic.

How do I know if there are lead pipes in my home?

If your home was built before 1970 it may have lead pipes. If it was built after 1970 it is unlikely to have lead pipes, as for drinking water supplies the installation of new lead pipes and the use of lead solder to join pipes has been banned in the UK for more than 25 years.

Even in properties with no lead pipework there may be other sources of lead in drinking water, such as brass fittings or improperly used lead-based solders.

Each property is different. However, start by checking the incoming pipework behind your kitchen cupboards or under the stairs – this is also where you would normally find your stoptap. Find the pipe leading to the kitchen tap. Unpainted lead pipes are dull grey in colour. They are also soft. If you scrape the surface gently with a coin, you will see shiny, silver-coloured metal beneath if the pipe is made of lead.

Always wash your hands thoroughly after doing this 'scratch test', which is featured in this video

If in doubt, ask a WaterSafe approved plumber or your local water company for advice. You can also ask your water company to test the water at your kitchen tap.

Why is it important to use lead-free solder to joint copper pipes?

For drinking water supplies the installation of new lead pipes and the use of lead solder to join pipes has been banned in the UK for more than 25 years. However, it is still possible to buy lead solder and cases of high lead in drinking water are still being recorded following its use by DIY enthusiasts or unqualified plumbers who are unaware of the danger.

Using lead-free solder to joint copper pipes which are used for drinking, cooking and washing isn’t just a legal requirement, it safeguards your drinking water.

Under the Water Fittings Regulations and Byelaws, the use of lead solder for jointing copper pipes is prohibited in plumbing systems which supply water for drinking, cooking or bathing. Solder containing lead can only be used on water installations not used for drinking, such as closed circuit central heating systems.

Your water supplier will be able to test the levels of lead in your water if you’re concerned. Water suppliers recommend households and businesses use WaterSafe to find approved plumbing businesses whose plumbers have undergone specific training in the Water Fitting Regulations and Byelaws.

What can I do to reduce lead in my water?

If your home has lead pipes there are short-term measures you can take to reduce the amount of lead in your water. Run the tap to remove water that has been standing in the pipes for long periods, for example, overnight, or if no one has run the taps for several hours. Draw off a washing-up bowlful of water from the kitchen tap once or twice to clear the water which has been standing. This doesn’t need to be wasted, but can be used to water plants or the garden.

In the long term, replacing the pipes is the best solution and you can discuss this with your water company as they may be able to co-ordinate this with replacing their section of the pipe.

One thing to remember - your existing lead supply pipe may have been used for electrical earthing, even though this has not been allowed for new installations since 1966. So, if you alter or replace your lead pipework you may also need to get advice from your electricity supply company or an approved electrical contractor.

Who is responsible for replacing the lead pipes in my property?

The water supply regulations* set strict lead standards for customers’ drinking water supplies. The maximum concentration allowed is 10 micrograms per litre, the same as one part in 100 million.

Many water suppliers already have programmes in place to replace any lead pipes they find on their own network.

However, homeowners and businesses are responsible for all pipes on their property – including internal pipes and the underground supply pipe which connects your home or business to the public water main.

If you’re replacing pipes within your boundary, make sure you contact your local water company, as they may be able to also replace the pipes beyond your house and garden.

WaterSafe and water companies advise replacing all lead pipes with new copper or plastic pipes which have been approved for use with drinking water. A WaterSafe approved plumber is qualified to safely replace lead pipes in line with the  Water Fittings Regulations and Byelaws which protect public drinking water in the UK.

*The Water Supply (Water Quality) Regulations 2010 in Wales, The Water Supply (Water Quality) Regulations 2016 in England, The Water Supply (Water Quality) Regulations (Northern Ireland) 2007 and The Public Water Supplies (Scotland) Regulations 2014.

Legionnaires' Disease

What is Legionnaires' disease?

Legionnaires' disease is contracted by breathing in large numbers of the legionella Pneumophila bacteria. These bacteria are widespread in the environment and are able to thrive in warm water conditions. They can be found in water systems, such as hot water tanks, cooling towers and large air conditioning systems. They are more likely to be found in complex plumbing systems.

Water suppliers treat drinking water with chlorine to kill off bacteria. However, they can continue to thrive in plumbing systems which are not installed or maintained correctly, which is why WaterSafe urges homeowners and businesses to only choose qualified and knowledgeable plumbing businesses.

How can I prevent Legionnaires' disease in my home or business?

Top tips to avoid problems with Legionnaires' disease include:

  • Only use a qualified plumber
  • Ensure suitable fittings are used (WRAS-approved)
  • Keep the design of plumbing systems simple
  • Design a system so water is regularly turned over and does not stagnate
  • Ensure hot and cold water are kept at the correct temperatures
  • Businesses should follow the advice within the HSE approved code of practice L8 to ensure they meet their legal duties under the Health and Safety at Work Act 1974 to manage risks from legionella bacteria.

Covid-19 Update:

In May 2020, Water UK published guidance to building owners, landlords and managers on recovering buildings and networks after prolonged inactivity during Covid-19 to avoid risks of adverse water quality and potential risks to health – including legionella bacteria.

Hosepipe Safety

How can I prevent illness caused by backflow from hosepipes?

Many homeowners don’t realise how ill you can get if the water in your hosepipe “backflows” into your drinking water supply, or becomes contaminated by potentially lethal bacteria, such as Legionella, that can thrive in warm, stagnant water and lead to Legionnaires’ disease.

The following simple steps will help protect you and your hosepipe but if in any doubt, always seek advice from a WaterSafe-approved plumber who will be able to ensure you have the right safety measures in place.

  • DO fit an approved double check valve to hosepipes to prevent any water, or contaminants from the garden, ponds or paddling pools, flowing back into your mains drinking water supply
  • DON’T place hosepipes in drains, garden ponds, buckets or watering cans where they can be submerged as contaminated water could be siphoned back into your home’s drinking water pipework
  • DO keep your hose somewhere cool and out of the sun
  • DO turn off your hosepipe at the tap and ideally fully disconnect it when not in use
  • DO fit a self-closing flow control, such as a trigger spray gun, to prevent it being used when unattended.
  • DO gently run the water out of the hose before you use it - without any form of spray attachment on the end
  • DON’T use a hosepipe that has been sitting around and full of warm water to fill a hot tub. The warm water within the tub will allow any bacteria – including Legionella – to quickly grow

Shirley Cramer CBE, Chief Executive of the Royal Society for Public Health

said: “Getting the message out about hosepipe safety is of great importance for the public’s health.

“The RSPH welcomes WaterSafe’s release of their top hosepipe DO’S and DON’T’S - sensible and practical advice that will help prevent those who follow it from potentially contracting serious diseases such as Legionnaires’.”

For more information on the RSPH visit www.rsph.org.uk.

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