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Science

Water doesn’t always flow from a source

This article comes from the magazine Sciences et Avenir – La Recherche n ° 891 dated May 2021.

Of course, water is essential for our health. And for good reason, it constitutes 60% of our body. It is essential to maintain its temperature, ensure the good circulation of the blood, the oxygenation of the cells and the elimination of waste. But we also lose part of it – between 2 and 2.5L – during the day. A loss that must be compensated by contributions, contained in the diet (about 1L) or in the form of drinks (1.5L).

Tap water, a very controlled drink …

62% of drinking water comes from underground resources (source or deep water table) and 38% from surface water (rivers, rivers, lakes). From its collection to the consumer, it is subject to regular health checks (18 million analyzes each year in France) and must meet nearly 70 quality criteria, including flavor, absence of toxic substances (lead, arsenic, etc.), pathogenic germs, etc. Drinking water also provides mineral salts and trace elements which it is responsible for in contact with soils and rocks: calcium and magnesium in the form of carbonates, fluorine (the content of which is limited to 1.5 mg / l because excessive intake can cause fluorosis, damage to teeth and bones).

… but not completely free from pesticides

In 2018, 90.6% of the population was permanently supplied with water that complied with regulatory quality limits for pesticides (0.1 microgram per liter and per molecule at most). This means that nearly one in ten French people consume – sometimes temporarily – water that exceeds these thresholds. After reviewing the analyzes carried out in 2019 by the regional health agencies (ARS), which monitor the quality of tap water, the environmental association Générations futures pointed out the presence of carcinogenic, mutagenic reprotoxic molecules (CMRs) and endocrine disruptors. However, these molecules can act at very low doses and produce an effect even when their quantity does not exceed the legal limit, fears the association.

Not to mention that in certain French regions (Brittany, Center-Val de Loire, Pays de la Loire, New Aquitaine), the water from the distribution networks exceeds the standard of 50 milligrams per liter (mg / l) of nitrates and must not be drunk neither by pregnant women nor by infants.

MINERALS AND TRACE ELEMENTS: Mineral substances formed naturally in rocks and present in very small quantities in the body.
CARBONATED MINERAL WATER: Still water from different sources, to which carbon dioxide has been added under pressure at the factory at the time of bottling. Conversely, sparkling water naturally contains carbon dioxide.
MICROPLASTICS: Plastic particles smaller than 5 mm in size. This waste accumulates in soils, rivers, lakes and oceans, and thus ends up in the food chain.

RO water deprived of its minerals

Present on tables since the 1990s, filter jugs are composed of a carbon cartridge that absorbs chlorine, copper and lead. However, according to the National Food Safety Agency (ANSES), their absorption efficiency has not always been demonstrated. In addition, ANSES recalls that the cartridges must be regularly replaced and the water consumed within 24 hours in order to reduce the risk of microbiological contamination.

The technology of reverse osmosis units which are placed under the sink is different: it is based on the principle of reverse osmosis which consists of allowing only water molecules to pass through. These devices filter pesticides, nitrates and lead from tap water. Problem, as with reverse osmosis water available in some organic stores, the water is thus freed of its precious minerals (calcium, magnesium).

Sparkling waters are not for everyone

Meeting the same bacteriological and physicochemical criteria as those of distribution networks, bottled water does not require special treatment such as chlorination. Be careful in case of hypertension, because some sparkling or carbonated waters (Saint-Yorre, Vichy Célestins) are particularly rich in sodium. Consuming too much can also cause stomach bloating. Note that a bottle of water must be consumed within 48 hours after opening to prevent the development of microorganisms.

Traces of microplastics in bottled water

The magazine What to choose carried out analyzes on 20 brands of bottled water sold in France, and by way of comparison, on tap water. The results are rather reassuring: no microplastics were detected in tap water, nor in 11 brands of bottled water. The other nine contained only traces (1 microfiber per liter at most). Yet in another study of 34 mineral waters, German researchers found that they were contaminated on average with 118 particles of microplastics (polyester and polypropylene) per liter. This can be explained in part by the fact that in Germany plastic bottles are returnable and reused. However, those for single-use plastic bottles had 14.

Some flavored waters are too sweet

These natural mineral waters or spring water, still or sparkling, are added with natural or synthetic aromas (the label just mentions “aroma”) but sometimes also concentrated fruit juice (juicy). In this case, they have an average sugar content of 5%. It is therefore better to focus on unsweetened water or opt for “homemade” flavored water. Also avoid those that contain additives, whether sweeteners, preservatives or colorings.

No continuously strongly mineralized water without medical advice, by Prof. Jacques Hubert, Head of the urology department at the CHU de Nancy

“An adult should drink 1.5L of water per day, even 1.7L in the elderly. Spring or weakly mineralized waters (Évian, Volvic) are suitable for daily and long-term use, but some may also provide occasional benefits according to their physicochemical composition. Thus sulphated mineral waters (SO4 content> 200 mg / l) such as Hepar help to fight against constipation. Waters rich in magnesium (Mg2 + greater than 50 mg / l ) (Rozana, Quézac) would have an anti-stress and anti-fatigue effect but excessive intakes are contraindicated in cases of renal insufficiency.Finally, calcium water (Ca2 +> 150 mg / l) (La Salvetat, Contrex) makes it possible to help cover the daily calcium requirements (800 to 1000 mg / d) in people who are not very fond of dairy products. “

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