Taste and smells

Metallic tastes are typically caused by elevated concentrations of metals found in the domestic plumbing system. It can also be caused by water standing in domestic pipes that are affected by local warming from unlagged hot water or central heating pipework.

To avoid metallic, bitter or sharp tastes in your drinking water, never use water from the hot water system for drinking and cooking. Metallic or bitter tastes can be reduced by running the tap to flush out the water that has been sitting in the pipes before drinking.

These tastes may be the result of metal dissolving from copper, iron or galvanised pipes in the plumbing system. This can also happen after new metal pipes are installed but the taste will reduce over time as the pipework becomes conditioned with a protective mineral layer which prevents the metal from dissolving.

Musty and earthy tastes or smells can be caused by the growth of harmless bacteria in domestic pipework. This can happen in sections of pipework that have a low usage or are subject to local warming.

Because the water may not have moved in the pipework for a prolonged period it can develop a musty taste and smell if it is left to stagnate. Before using water for drinking and cooking, run your tap for a few minutes to flush out any water standing in the pipes.

Musty smells can also develop when cold water pipes are warmed by being too close to hot water pipes. To avoid this, ensure that both hot and cold water pipes in your property are separated and insulated and that you only drink water directly from the mains supply.

Unapproved plumbing materials and fittings can also cause musty odours.

Medical or TCP tastes are commonly caused by new appliances, such as a kettle. If you have recently bought a new kettle and your hot drinks don’t taste right, try boiling some water in a saucepan and see if the taste goes away to see if the kettle is the cause.

These tastes can also be caused by degraded tap washers or flexible inlet pipes on washing machines and dishwashers. To check if an appliance connection is causing the taste, turn off the water supply to the appliance using the service valve at the point where the flexible pipe connects to the mains supply.

If the taste disappears after running the tap for a short while when this valve is closed, this suggests that the flexible pipe is the source of the problem. The best solution is to have a one-way check valve fitted to the connector just before the flexible pipe to prevent water from flowing back into your taps.

Some taps use flexible or braided hoses to connect the tap to metal pipes, which can cause medicinal tastes. Eliminate these by ensuring your drinking water fittings are approved.

Chlorine is added to water to disinfect it and make it safe to drink – it is a legal requirement to disinfect water.

Chilling tap water in the fridge will reduce the chlorine taste and smell. It should be kept covered in the fridge for no more than 24 hours after being drawn from the tap. After that time the water is at risk of bacterial contamination.

The level of chlorine in the water supply may vary according to:

• the time of day – it may seem higher in the mornings and at dinner time due to increased water usage
• how close your home is to a water treatment centre – the nearer your home, the higher the level as the water has travelled less distance
• the water treatment centre supplying your home – if the centre supplying you changes, you may notice a change in taste.

The taste of chlorine can be removed using a water filter. Please follow the manufacturer's instructions when using one.

Plastic tastes are often caused by the use of unsuitable plumbing materials.

Only materials approved for use in contact with drinking water should be used.

Salty tastes can be caused by incorrectly installed ion water exchange water softeners. This may result in a backflow which can allow salty water from the softener to syphon back into the drinking water system.

To avoid this, always follow the requirements of the Water Supply (Water Fittings) Regulations 1999 and the British Water Code of Practice when installing water softeners.

We don’t recommend drinking softened water. One tap in your home – ideally the kitchen cold water tap – should be reserved for drinking water and remain unsoftened.

An eggy or sulphuric taste or smell is usually the result of your sink’s waste trap affecting your perception of the water – the water itself will not be affected.

You can check this by filling a clean glass with water from the tap and taking it into another room before tasting it again.

If the water tastes and smells fresher away from the sink, it suggests the waste trap is the cause of the smell.

Over time, organic matter (such as food waste and soap) can accumulate on the walls of the drain and bacteria can grow on these organic deposits.

As the bacteria grow and multiply, they can produce gases that may smell like eggs or wastewater. To get rid of this smell, clean and disinfect the drainpipe below the sink.

Petrol, diesel or solvent tastes and smells can be associated with chemical or fuel spills on the ground near water pipes. These have chemicals that can soak through a driveway or soil and permeate plastic water pipes to cause an unpleasant taste or smell.

If you become aware of a spill or notice an oily taste or smell to your water, please contact us.

To help prevent oil leaks and spills in your home, you could:

• check that the oil tank and associated pipework are in good condition
• get your tank inspected by a qualified engineer
• ensure your tank is locked and secure from theft
• monitor the level in the tank
• ensure fuel storage tank installations meet local building regulations.