Common water quality problems

Drinking water has to comply with the most stringent standards and water suppliers go to great efforts to ensure it is delivered safely to their customers. However from time to time sometimes problems can occur, here is some advice on the most common water quality problems.

Should you have any concern about the quality of your water you should contact your water supplier.




A. 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

Solution - 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.

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 causing 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.


A. Blue or green looking water is often due to copper from new copper pipe work, either in new houses or where new pipe work has been has been installed in older properties. This is because these new copper pipes are settling in.

Solution - To help prevent this from happening new pipe work needs to be flushed thoroughly and plumbing systems should be drained down when not used immediately after installation.

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

Solution - For information about how to check your toilet cistern please check our guidance

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


A. 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 travelling through the mains where there has been a burst mains pipe, or from a faulty plumbing fitting.

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

Solution - You can check if this is the problem by running a glass of water and allowing it 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 closest to the pipe where it enters in to the property (usually the kitchen tap). Run it on a slow steady flow, while the tap is running turn the internal stop tap on/off 4-6 times to help release any 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.

Taste and odour


A. 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 in protecting public health and it is added to drinking water as the final stage of treatment in order to kill any harmful germs that may be present.

Water suppliers monitor chlorine concentrations closely and try and keep the levels as low as possible whilst keeping supplies safe. Concentrations can vary throughout the day and through the seasons, and may be higher if you live close to a water treatment works.

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

Solution - 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.

Solution - 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.

Caution - Any device which is ‘plumbed-in’ must comply with the Water Supply (Water Fittings) Regulations and Scottish Water Byelaws. If not properly manufactured and maintained, such devices may cause problems with water quality.

Sometimes chlorine reacts with materials used for tap washers, anti-splash devices and seals in kettles causing 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 non-metallic plumbing materials, such as rubber washers, or hoses if you have appliances (such as vending machines, dishwashers and washing machines) plumbed in close to taps used for drinking water.

Solution – either change the hoses for those which have shown to be of a suitable quality and standard, as defined in Regulation 4(2), 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.


A. 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.

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

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

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


A. Some plumbing materials that come into contact with the water supply in homes, offices or factories can give water unpleasant tastes and odours. When water stands 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 those that 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 onto the incoming water main.

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

Solution – either change the hoses for those approved under the 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.

Solution – remove the hose from the tap when not in use and check that a double check valve is fitted and functioning properly. A qualified plumber will be able to offer advice on this issue.

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 can change the taste of your water. The most commonly affected areas are the kitchen tap and the stop tap.

Solution – replacing old and worn out washers and tap seats may help improve the taste.

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

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


A. Sometimes taste problems can arise after water has been boiled. As a general rule, if your drinking water is satisfactory before 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.

Solution – if the kettle is new allow it to settle down 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.

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


A. If there is a taste or odour of petrol or diesel 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 purposes until you have sought advice from your water supplier.

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 at the premises, i.e. a car or motorbike leaking oil. This is the most common cause for this type of issue.


A. Sometimes a sewage or stagnant type odour can emanate from a sink or plug hole, indicating a possible blockage or build-up of waste materials, making the drinking water appear as if it has an odour. Filling a glass with water and smelling it in a different room, away from the kitchen sink, will help to determine whether the odour is genuinely from the water or not. If you think it is the water please contact your water supplier immediately.

Solution – if the odour disappears when 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.