Unit of measurement
Dilution number
World Health Organisation Standards (1993)
Acceptable to consumers and no abnormal change
Standards for private water supplies in England (2016)
3 at 25ºC
Standards for private water supplies in Scotland (2006)
Acceptable to consumers and no abnormal change
Standards for private water supplies in Wales (2017)
Acceptable to the consumer
European Union Drinking Water Directive (1998)
Not mentioned


Taste problems are responsible for most complaints about water quality. Substances which can be responsible for taste problems include chloride, sulphate, sodium, copper, iron, zinc, magnesium, calcium, chlorophenols and chlorine.

Some common taste issues with drinking water from private water sources include the water tasting:


​The presence of high concentrations of chloride ions or sulphates can result in your drinking water having a salty aftertaste. Unfortunately, if these concentrations are too high, they can have undesirable effects. Excessive sulphates in your tap water can have laxative effects, meaning anyone that drinks the water could end up with a bad stomach. Too many chrloride ions can cause damage to pipes and discolour steel fixtures and fittings. If you begin to notice a salty taste to your water, then testing could confirm the cause, meaning that you can take swift, effective action.


​Although tap water contains naturally occurring minerals such as calcium and iron when these are present in higher quantities, they can produce a sweet aftertaste, especially in those with a more sensitive palette. A sweetness to water can also reflect an imbalance in your water's pH which ideally, should be neutral (7 on the pH scale).


​Water which is bitter or metallic in taste can be as of the result of water sitting in iron, copper or galvanised pipes. Sometimes this taste can be rectified by simply allowing the water to run from the tap for a little while before drinking. A bitter or metallic taste can, however, signal more significant issues, such as corrosive water which is affecting the plumbing and requires treatment.


​Plumbing pipes and fittings can also be made from plastics and/or rubbers which can result in water tasting unpleasant due to small amounts of the materials being dissolved into the water. Sometimes, internal plumbing errors can result in water from appliances such as the washing machine and dishwasher, which have rubber hoses and components, returning to the mains supply and making its way to your taps. Usually, a plastic or rubbery taste to your water is not indicative of anything harmful, but it is always worth getting to the root of the issue if it persists.


​Water which has passed through peaty soil can take on an earthy or musty taste. What's more, there are several types of naturally occurring bacteria and algae found in lakes, reservoirs and rivers which produce substances, that while harmless, can generate a musty taste or smell. This taste can become more prominent in warmer weather as a result of an algal bloom. The increased temperatures and sunlight make the perfect climate for algae which blooms on the various water source surfaces, Even when the algae are removed from the water during treatment processes, the taste that has been generated remains. Such bacteria can also grow within the pipes and around the taps in your home.


​Water can taste like chlorine due to chlorination treatment processes that are undertaken. In fact, chlorination is a problem for Water Authorities because drinking water should be dosed at such a level to achieve a satisfactory bacterial kill, but not impart a significant taste. The level of chlorination, therefore, has to be carefully monitored.


​Chlorine can also be the cause for an antiseptic, 'TCP', or disinfectant type taste to water. It can react with plastics or rubbers within the plumbing system or appliances to generate this harmless, yet unpleasant flavour. Unfortunately, this taste can also be the result of the presence of high levels of chlorophenols in your water. Chlorophenols can enter a water supply when they are being made or used as pesticides as they stick to soil and sediments that are located at the bottom of riverbeds, lakes and streams. Low levels of chlorophenols are naturally broken down within the space of a few weeks by microrganisms but higher levels can cause damage to the liver as well as having an effect on the immune system.

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