Tap water or bottled water:
What is the difference ?
Of all food products, tap water is subject to the strictest controls. In France, we consume an average of 150 litres of tap water per day and per person (PDF) for our various uses: diet, personal hygiene, household cleaning, laundry, etc.
This water comes mainly from groundwater or surface water (rivers, canals, lakes, reservoirs) catchments. Most water taken from the natural environment is treated to ensure permanent compliance with the quality limits or reference values of around 60 microbiological, physico-chemical, radiological and organoleptic parameters set by the French Public Health Code.
To disinfect and kill bacteria in the water and to protect its quality as it travels through the pipes, managers have to add chlorine. Even in small amounts, it is not always pleasant for the consumer. To get rid of the smell or taste of chlorine in tap water, you can aerate the water by letting it stand for 30 minutes in a jug before drinking it.
Did you know?
To prevent bacteria from growing in the water, the Romans used to let it flow continuously (aqueducts, houses, etc.)!
Bottled water, whether natural mineral water or spring water, comes exclusively from an underground source and must be microbiologically safe. It cannot be disinfected using chlorine, for example. As its name suggests, bottled natural mineral water contains minerals, some in greater concentrations than in tap water.
Depending on its composition, some mineralised water can have health effects and is recommended for special needs: water containing sulphate, for example, has a laxative effect, other types improve calcium intake, etc. In addition, some quality limits set for natural mineral water are different to those set for tap water. This is particularly the case for fluorine, which has a higher value for natural mineral water.
Lastly, specific quality limits must be complied with in order for the words "suitable for infant feeding" to appear on the labels of natural mineral water and spring water.
How much should I drink?
It is recommended that adults drink a least 1.5 to 2 litres of water per day and should not wait to feel thirsty. This is especially important for the elderly, who often have a reduced sense of thirst.
Certain types of mineral water should be consumed sparingly because of their sodium concentration, and may present contraindications. Any therapeutic use of natural mineral water should be based on medical advice. This is because highly mineralised water can be harmful if it becomes the only daily drink. For example, above 250 mg/L, sulphates can promote diarrhoea, and above 900 mg per day in adults, calcium can induce kidney stones.
How should water be stored and which containers should be used?
Bottled water should not be consumed beyond its expiry date. To keep it at its best, it should be stored away from the sun and heat, in a cool place such as a cellar.
Avoid using a plastic bottle as a flask or container for storing tap water, as the chlorine in tap water can react with the plastic. Opt instead for containers made of glass or stainless steel, for example, which are more resistant than plastic to chlorine and the possible acidity of the water. You can store tap water in the refrigerator for 24 to 48 hours.
Did you know?
Regardless of which container you choose (plastic, glass, stainless steel, etc.), the materials used are not completely inert in contact with water. This is why manufacturers are obliged to comply with regulatory limits on the migration of compounds from the container into the water.
What is the correct way to use these containers to limit the health risks?
With containers for individual use such as reusable water bottles or insulating flasks, it is essential to clean them regularly using a swab to remove any biofilm from the inside walls.
Moreover, you should avoid allowing several people to drink from the same bottle, as bacteria could be deposited and then grow on it.
Filter jugs: an alternative to bottled water?
More than 20% of French households use a water filter jug to get rid of the taste of chlorine, or to remove limescale, lead and residues of organic matter. In its March 2017 report on the subject, ANSES recommended that users:
comply with the user instructions and any restrictions or precautions for use: cleaning of the jug and regular replacement of the cartridge (generally every four weeks) mainly to avoid the risk of microbiological contamination;
keep the water filter jug and its water in the refrigerator and consume the filtered water promptly, ideally within 24 hours of filtration, because the chlorine has been neutralised and this could cause bacteria to grow again.
What does ANSES do to ensure the quality of drinking water all the way to the consumer's tap?
It provides scientific and technical support for the drafting of national and European regulations on drinking water and assesses the health, biological and chemical risks at each stage of water production, from the source through to the consumer’s tap.
To do this, it is supported by the Water Risk Assessment Unit, the National Reference Laboratory for Hydrology, the Expert Committee on Water, and its working groups.