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.