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Water quality information

Find out general information about your water below or if you would like to learn more about the water quality in your area you can generate a report.

Why isn’t my water clear?

We go to great lengths to make sure your drinking water is supplied to the very highest standards. However, on rare occasions it may appear discoloured or cloudy. This can be caused by a burst water pipe that can mean water flows through the pipe quicker than normal. When this happens, the deposits that normally sit at the bottom of the pipe can be stirred up and this can make your water appear orange or brown. These deposits are usually nothing to worry about, but we understand you may not want to drink the water while it’s discoloured. Head to our Check my area page to see if there’s any burst mains or other activity going on. The best way to clear discoloured water is to run the tap closest to your internal stop tap (normally your kitchen tap) on a really steady flow, about the thickness of a pencil, for 20 minutes. Don’t be tempted to give the tap a good blast as that can make the problem worse.

If you’ve tried running your tap steadily for 20 minutes and it’s still discoloured contact our team and we’ll investigate. If your water appears milky or has lots of bubbles in it this may be caused by changes on our network such as bursts or emergency repair work. If you fill a glass of water and it clears from the bottom upwards then your water is a little more aerated than usual. The issue will normally resolve itself, but if it’s been ongoing for a little while and you’re beginning to worry simply get in touch.

What to look out for

Occasionally the natural characteristics of the water itself may give the water a yellow or brownish tint, however Hafren Dyfrdwy processes are designed to remove such colour. This is the case when water comes from upland areas or groundwater sources rich in iron. If it’s milky or cloudy, the cause is an excess of bubbles in the water, often caused as a result of a faulty fitting. If you leave it standing for a minute, you’ll find the completely harmless bubbles should soon disappear.

Our sources are of generally high quality and have appropriate treatment to ensure safety and quality at the customers tap.

All water sources contain a number of naturally occurring compounds and minerals such as calcium, iron and magnesium in varying concentrations that have an effect on the waters’ taste. Without these minerals water would taste flat and unappetising. Customer sensitivity to these mineral tastes varies but can be particularly noticed by those travelling or moving from another part of the country. There are several common causes of tastes and odours in drinking water, these are highlighted below. If any of our customers are concerned about their water they should call us on 0800 085 8033.

Medicinal taste

This is often caused by a chemical reaction between chlorine and man-made plastic or rubber fixtures such as tap washers and dishwasher hoses. If you have recently changed an appliance this is the most likely reason for the sudden change in flavour.

Earthy taste

Surface water that passes through peaty land can sometimes develop a musty taste or odour. This is particularly the case after long periods of warm, dry weather. All of our treatment works have processes in place to minimise any unpleasant natural smells.

Metallic taste

If water has been in sustained contact with copper, iron or galvanised pipes it can sometimes develop a slightly bitter taste. You might notice this after going away on holiday for a few weeks. Simply running a tap for a minute or two when you get home will generally fix the problem.

Petrol odour

If there has been a spillage of petrol, diesel or heating oil on your driveway or garden it may contaminate your water supply. This is because these substances are able to permeate through plastic service pipes. If you believe your water has a petrol or solvent taste it is important that you call us on 0800 085 8033 immediately and we will arrange for an investigation of your supply.

Chlorine odour

Levels are present in water supplies to maintain its safety and quality. Levels can still vary depending on the distance of the customer's house from the water treatment works, the time of year and even the time of day. A chlorine taste can be reduced by filling a jug and keeping it in the fridge for a few hours.


Time for a few hard facts

Water hardness refers to the amount of naturally occurring calcium and magnesium that’s present in the water. It varies in hardness from source to source, but is generally harder in limestone areas than areas with insoluble rock such as Granite. In case you were wondering, it’s expressed as the equivalent amount of calcium carbonate in parts per million (mg/g), or sometimes in degrees. That’s  the science lesson over. The important thing to know is that even when the water is very hard it’s not harmful to your health, however it may contribute to worsening of some existing skin conditions such as eczema.

The effects of hard water

Hard water can cause scale to form in kettles, steam irons and around taps and showerheads. It can also affect your washing machine and dishwasher. Luckily you’ll find lots of scale removing products at your nearest supermarket. If your water is hard, you may find it leaves a layer of dirt or froth around your basin and bath. You’ll also need to use a little more soap or powder when on washing up and laundry duty.


Fluoride is naturally present in all water supplies at varying levels.

Some water supplies contain fluoride naturally, for instance where water is taken from an underground source where the water has passed through rocks with fluoride containing minerals in them. The natural background level of most source waters in the UK is below 1 part per million (mg/l).

Some water companies, at the instruction of health authorities, add fluoride to the water to help tackle tooth decay. We do not artificially fluoridate any of our water.

Hafren Dyfrdwy and all water providers in the UK have a legal requirement to disinfect drinking water supplies and ensure the water is free of any microorganisms or other contaminants that may cause ill health.

Most of our water comes from surface sources, such as rivers, upland and lowland reservoirs. As rain falls and washes overland into rivers and reservoirs, it picks up various materials which can contain large numbers of harmful microorganisms, which must be removed by treatment and disinfection

Why is chlorine added to water?

For over 100 years, chlorine has been added to water supplies around the  world to make sure it’s safe to drink. Most of our water comes from sources such as rivers and reservoirs. As rain falls and washes overland it picks up materials that can contain large numbers of harmful microorganisms that must be removed by treatment and disinfection.

How much is used?

Chlorine is first added at the treatment works, then topped up as necessary as it travels through the underground mains to your home. It goes without saying that chlorine levels are kept to the minimum necessary to ensure continuous protection and are constantly monitored by Hafren Dyfrdwy. Typical levels are between 0.1-0.5 mg/l. To help put this into perspective, a swimming pool commonly uses 5 mg/l.

The taste factor

If you have a sensitive palate, you may occasionally detect the slightest trace of chlorine in your water. This is because chlorine levels are monitored all year round with additional low levels added to make sure your water remains safe to drink. A good tip for reducing the taste is to keep a jug of fresh tap water in the fridge for a few hours, as this will allow the chlorine to dissipate.

What is cryptosporidium?

Cryptosporidium is a microscopic organism that causes a type of gastroenteritis called cryptosporidiosis in humans and other animals. It’s most commonly contracted when travelling abroad, through contact with those carrying the organism or when children come into contact with infected farm animals or faeces. The symptoms of illness include a watery diarrhoea, nausea, vomiting and/or abdominal pain.

Can it occur in drinking water?

Cryptosporidium won’t occur when water is properly treated. However, unlike bacteria, cryptosporidium survives in an egg-like body making it more resistant to standard disinfection and enabling it to survive for long periods. Outbreaks of cryptosporidiosis related to drinking water are extremely rare in the UK and there has never been an outbreak associated with water supplied by Hafren Dyfrdwy.

How to avoid cryptosporidiosis

Like so many things, the best cure is arguably common sense. Always wash your hands thoroughly with soap and warm water before preparing food, after  handling raw food, after going to the toilet and after contact with pets or farm animals. Always avoid untreated water and when possible don’t use drinking water or ice in countries that may have unsafe water supplies. Also try to avoid swallowing water in lakes and swimming pools.


Why is there lead in water?

We work tirelessly to supply virtually lead-free water. However, some older properties may be connected to our water pipes by a lead service pipe where lead can pass into the water. It can also get into your water from lead-based soldered joints used on copper pipes or from lead plumbing. As it can be harmful if it builds up in the body, it’s important to identify if you’re at risk.

The Department of Health advises that lead can be harmful if levels are allowed to build up in the body. Therefore, it makes sense to try and reduce the amount as much as possible, particularly if you are pregnant or have young children. For further health advice please contact your GP.

How to tell if you have lead pipes

If your property was built before 1970 you may have lead pipes, however those built since are more likely to have plastic or copper pipes. The simplest way to check is to first find the point where the water service pipe enters your property (it’s usually under your kitchen sink or stairs). Scrape the pipe with a coin and if you see a shiny, silver-coloured metal underneath you’ll know it’s a lead pipe.  

I think I have lead pipes, what should I do?

  • Avoid drinking water that has been standing in the pipes for long periods. Simply flush the water by running the cold tap first thing in the morning and when you get in from work for at least two minutes.
  • Only use water from the cold water tap in the kitchen for cooking, drinking and when making up baby formula.
  • Use water filters designed to remove lead, however this should only be used as a short-term measure.  

Should I get my water tested?

If you discover that you do have a lead service pipe or plumbing in your property, we’re happy to come out and test the water for you. Simply contact our team on 0800 085 8033 or  fill out this form  to arrange this.

What are nitrates and pesticides?

Nitrates and pesticides are commonly used by farmers and gardeners around the world to ensure bumper crops and pest-free plants. Nitrate is a naturally occurring compound of nitrogen and oxygen that’s present in all vegetation. It’s often added to plants in the form of manure and chemical fertiliser. The UK and European standard for nitrate in drinking water is 50 parts per million. Pesticide is a broad term for a wide variety of different chemicals including insecticides, herbicides, fungicides and algaecide. All are used in a strictly controlled way that safeguards our farm produce, gardens and greenhouses from unwanted pests. The UK and European standard for pesticide in drinking water is a rightly stringent 0.1 parts per billion.

Can they contaminate my water?

It’s possible for both nitrates and pesticides to enter groundwater sources through ground percolation. They can also enter rivers and open reservoirs through surface run-off. To help manage this, we work closely with landowners, industries and the Natural Resources Wales to keep levels to UK standards while using our collective brainpower to come up with innovative alternatives.

Planning for the future

In the few areas where raw, untreated waters have relatively high nitrate levels we have developed other low nitrate sources and blended the two to dilute the concentration. We have also put plans in place for the installation of nitrate removal plants as a further measure to ensure the quality of your drinking water for many years to come.  Furthermore, we continue to work closely with farmers in order to maintain our position as industry leaders in catchment management


What exactly are biofilms?

Every surface in the natural environment is covered in microscopic organisms such as bacteria, moulds and fungi that are invisible to the naked eye. A biofilm is the name we give to these layers of microbes. In most cases they’re completely harmless, while some are even beneficial. The only time we tend to ever really notice them is when they rot food, make us ill or cause that infuriating black gunge on grout. 

Are they harmful?

Biofilms are rarely more than a nuisance, however it’s never a good idea to allow the growth of large numbers of microbes. Why? Because higher concentrations can infect cuts or wounds, while some moulds can cause an allergic reaction in susceptible people. Microbes love moist, warm environments such as kitchens and bathrooms, so it pays to keep these areas as dry and clean as possible at all times.

How do I get rid of biofilms?

Biofilms can be easily removed by spraying them with household disinfectant sprays and simply wiping them away. Sprays containing bleach will remove any staining caused by a biofilm unless the microbes have infiltrated soft surfaces such as silicone sealant. The other most common biofilm is the black slime found in your washing machine drawers. Running the machine at 60°C or above once a week will kill the microbes and may also reduce growth, as will leaving the drawer open after use to allow it to dry out between loads.


Filtering out impurities

The water we supply is of the highest standards, however you can use water filters at home to remove any harmless residual substances from your drinking water such as chlorine and temporary hardness. The simplest filter to use is a jug filter, which uses easy to change cartridges to block impurities. It’s generally recommended that these jugs are kept in the fridge and that the water is consumed within 24 hours. The second type are plumbed-in filters, which are permanently installed into the cold water supply pipe or main supply feed to the tap. In all cases, filters must be strictly maintained according to manufacturer's instructions.

Why use water softeners?

Water softeners are often used by people living in hard water areas to help prevent the build up of scale in their boilers, dishwashers and kettles. When having a water softener fitted it’s strongly recommended that you keep an unsoftened water supply for drinking water. We don’t currently soften any of our water supplies at Hafren Dyfrdwy.

When should soft water be avoided?

It’s important to avoid using ion-exchange softened water in babies feeds or for people on a low sodium diet due to the increased sodium content from the softener. It’s strongly recommended by medical and plumbing experts that a separate supply be kept as an alternative to the softened supply. We also recommend you use unsoftened water for watering plants and topping up steam irons.