Taste and odour

Different tastes are often caused by differences in the hardness of water. Most of the water in our region is naturally hard as it comes from groundwater sources.

The water has trickled down through layers of chalk, limestone or rock underground and has a high mineral content with lots of calcium and magnesium.

Find out more about hard water.

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 odours can be caused by the growth of harmless bacteria in domestic pipework. This can happen in sections of pipe that have a low usage or are subject to local warming.

Before using water for drinking and cooking, run your tap for a few minutes to flush out any water standing in the pipes. This water can be used on your houseplants.

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.

Musty odours 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 direct from the mains supply.

Unapproved plumbing materials and fittings can also cause musty odours.

While we optimise treatment processes to prevent unusual tastes and odours in drinking water, naturally occurring organic compounds can be present in our surface water sources at certain times of year.

Medicinal or TCP type tastes are usually traced to unsuitable or degraded tap washers, rubber tap extensions and other fittings, such as sealing rings in electric kettles and flexible hoses on washing machines and dishwashers.

If these have even very low concentrations of phenolic chemicals, traces can dissolve in water and react with the chlorine forming chlorophenols, including TCP.

Although these are not considered harmful, they can cause noticeable tastes and odours at extremely low levels.

A frequent cause of TCP taints in the water supply is the flexible cold water feed pipes on washing machines or dishwashers.

To check if an appliance connection is causing the taste issue, turn off the water supply to the appliance using the service valve at the point where the hose connects to the mains supply.

If the TCP taste disappears after running the tap for a short while when this valve is closed, this suggests that the flexible hose 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 backflow. Check valves are simple to install and can be bought from most plumbing merchants and DIY stores.

Some taps use flexible or braided hoses to connect the tap to metal pipes. Some of these may cause medicinal tastes. The best way to eliminate these is to ensure that all your drinking water fittings are approved.

If you have a second mains supplied tap in the house, try using water from this. If you notice no medicinal taste, then the cause may be a tap washer in the original tap.

Another cause of TCP taints in the water supply is the deterioration of materials from within your kettle, even when new. Always follow the manufacturer's instructions when using a new kettle for the first time.

If a TCP taste is only present in hot drinks, boil some water in a clean saucepan. If the taste is no longer apparent, it suggests that something in the kettle is responsible.

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 works - the nearer your home, the higher the level as the water has travelled less distance
• the water treatment works supplying your home - if it 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.

If a property has been unoccupied for a while, it is possible that eggy or sulphur tastes or odours might be noticed.

These are usually a result of the odour from the waste trap of the sink 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 away from the sink 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 odour.

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, such as heating oils, petrol or diesel, 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.

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.

You may also want to contact your home insurance company to check that your policy covers appropriate risks relating to an oil tank.

Remember that fuel storage tank installations must meet local building regulations. For more information visit OFTEC (Oil Firing Technical Association).

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

Bits in water are usually caused by:

• limescale which can become discoloured by traces of metal from pipework. These bits are usually white but can sometimes appear green/blue due to copper or brown/black as a result of iron pipework. Sometimes scale particles from the bottom and side of kettles can be poured accidentally into drinks. Films of fine particles can also float on the surface of hot drinks. Fully emptying and rinsing your kettle before boiling can help to reduce this
• water filters or water softeners - please contact the manufacturer with any queries
• limescale or particles of corroded iron pipes dislodged from the pipes can appear as gritty or sandy bits in water
• microbial growth - the best way to avoid this is to keep taps and surfaces clean.