Tastes and odours

In the UK we use water from many different sources, including chalk boreholes, upland reservoirs and lowland rivers, and each source has its own characteristic taste.

It’s easier to spot hard and soft water but you may have noticed that drinking water can taste different as you move around the country. Some people are very sensitive to any changes in taste or odour.

Fortunately, unpleasant tastes and odours in mains water are rare and are often easy to resolve. Some useful advice and solutions to improve water quality can be found below. Any tastes or odours you notice from stored water or your hot water system should be investigated by an approved plumber particularly where the cold, mains-fed tap is not affected. 

Dealing with common tastes and odours

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Listed below are some common tastes and odours that you might notice.

• Antiseptic / TCP in cold water from the mains tap or in boiled water

  Sometimes cold water drawn from the tap may have a taste often described as being like antiseptic or like TCP, it can be more obvious when the water is warmed and so you may only notice it in boiled water or hot drinks. This is normally caused when chlorine reacts with rubber and plastic materials such as blue washing machine or dishwasher hoses.

  Advice to eliminate this can be found in the section below.

  When the drinking water tap is turned on, a small amount of the water in these hoses can be drawn back into the cold supply. To check whether these hoses are causing the taste, turn off the supply to the appliance or disconnect the hose and check the taste again. (see image below to isolate cold water hose)

  What can you do?

  For appliances, you can change the hose to one approved for food use (normally white in colour). Or fit a double check valve, this will prevent water within the flexible hoses, returning to your drinking water tap and altering the taste.

  For more information please visit Water Regulations Advisory Scheme (WRAS).

  For garden hoses, remove the hose from the tap when not in use and make sure that a double check valve is fitted and working properly between the tap and the hose. An approved plumber can advise you.

  It is also possible that your tap washer or some part of the tap is the cause. If you have recently installed new taps you should suspect this as a possible cause. To rule this out for certain, you need to check if the washers conform with an appropriate Standard. Approved products are listed on websites such as the Water Regulations Advisory Scheme (WRAS). In some cases newer domestic taps have flexible hoses to assist in the fitting, these are also known to have the same effect so if you have recently replaced them this could be the cause.

  Always remember to choose approved fittings. 

  Sometimes taste problems in boiled water can be due to plastic kettles. This is caused by similar plastics used within kettles as described above. If you try boiling fresh water in a saucepan on your hob or stove, you can tell if your kettle is the cause.

  If the kettle is new, it can help if you allow a layer of lime scale to build up inside by boiling and then disposing of the water a few times. Try to avoid de-scaling the kettle frequently. It’s better to boil only the amount of water you need each time, so don’t re-boil water. After boiling, empty the unused water, rinse the kettle and fill with fresh water.

• Chlorine

  To ensure the water you receive at your tap is of high quality, a small amount of chlorine is left in the drinking water supply after it leaves our treatment works. This small amount helps to maintain the quality of the water within our pipe network and make sure that water arrives at your property free from harmful bacteria. Chlorine has been used to treat drinking water for over 100 years and the low levels we add are carefully controlled and continually monitored.

  We check chlorine levels continually at our treatment works, and right through to our customers’ properties. Sometimes the smell of chlorine might be more noticeable, for example if the water has warmed up or been standing in your pipes overnight. If you are sensitive to the chlorine and notice a slight taste or odour, a simple solution is to cool your water by filling a jug of tap water and placing it in your fridge, keeping it covered. This will allow some of the chlorine to disperse and in a few hours the taste or odour will improve. You should remember to replace any unused water after 24 hours.

• Metallic / bitter

  Customers’ internal pipework can be made of metal and this can cause a metallic or bitter taste in new installations or after changes to your domestic plumbing. This is most obvious after water has been standing in pipework for a while, for example overnight. It might also happen where there are long runs of pipework. It is more common when the pipework is new, the taste should improve with time as a thin layer of limescale will form on the inside of the pipework and reduce the taste transferring into the water.

  Where mains water gets warmed, by pipes nearby, for example, this can affect the taste. When this occurs you should check the layout of pipework and how close the cold and hot water pipes are. Affected pipework should be lagged or re-routed, as necessary. Running the tap to clear any water standing in the pipe should also help. It’s a good idea to collect it in a container so it can be used elsewhere such as watering household plants.

• Rotten / stagnant

  Sometimes a rotten or stagnant type smell can seem to come from your water but usually it’s coming from a sink/plug hole. If there is a blockage or build up of waste materials in the drain, running the water can push bad smelling air into the room making the drinking water appear as if it has an odour. Try filling a glass with water and smelling it in a different room, away from the kitchen sink. This will help to show whether the smell is genuinely from the water or not.

  If the water smells fine away from the sink, you could try cleaning your sink/plug hole with a normal domestic cleaner. However, if the mains water still smells away from the sink, it could indicate a problem and you should contact us immediately.

• Petrol / diesel / oil

  If the ground around plastic water pipes becomes contaminated with fuel, for example after a spillage of diesel, oil or petrol from a car or from a fuel storage tank, the taste can sometimes be detected in drinking water. This may not happen immediately as it will take time for contaminants to soak into the ground and permeate the pipe.

  If you notice this type of taste or odour, or are aware of a leak or spill of petrol/diesel/oil on or near your property, it is sensible that you do not drink your water and contact us immediately to discuss the issue with a member of our Water Quality team who will assess the situation and let you know what to do.

  Particular things to consider if you experience this:

  • Do you have a vehicle parked for long periods of time that could have fuel leaking onto the ground?
  • Do you live near a petrol station?
  • Do you have oil fired central heating and oil storage at your property?

  All of this information could be valuable to our team, so please let us know if you are aware of anything like this when contacting us about the issue.

  Contact us immediately if you notice a particularly bad taste or a change in the taste that means you cannot drink the water from your mains-fed, cold water tap.