Water is the most abundant substance in all living things. On average, 60% of the human body is composed of water. As you read this, your 75%-water brain is processing information gathered by your 98%-water eyes. That level of water must be maintained. The simple actions of breathing, sweating, and digestion, all cause the body to lose water. Rehydration is vital for regulating body temperature and maintaining healthy body systems and joints.
For many years, health authorities recommended that adults should drink two liters of water per day. However, estimates of the actual amount needed vary. In the United States, the National Academy of Sciences, Engineering, and Medicine recommended that men should drink 3.7 liters of fluid every day, and women 2.7 liters. In Britain, the National Health Service recommends between 1.2 and 1.5 liters per day, depending on air temperature and activity level.
It does not all have to be pure water to meet the quota. The water content of food and other drinks also contributes to the total. Despite this, most adults in Europe and the US are thought to function in a constant state of slight dehydration. We should all be drinking more.
But in today’s society, there is a dizzying array of different types of water available. You can get it from the kitchen sink, or you can buy it in bottles. Even then, commercial water brands compete with claims that theirs is the healthiest. Should we be drinking spring water, artesian water, mineral water, distilled water, alkaline water, hydrogen water, or even collected rainwater? Despite the names and claims, is there really any difference?
What Makes Bottled Waters Unique?
If your water comes from a bottle, the International Bottled Water Association regulates what it says on the label. For example, only water that flows naturally to the surface from an underground source can be called spring water. It can only be collected directly from the spring or from a borehole tapping the underground formation that feeds it. Mineral water must contain no less than 250 parts per million of dissolved solids, and no additional minerals can be added after extraction.
Industrially purified water should be labeled with the process by which it was treated—for example, distilled water, deionized water, or reverse osmosis water. This way, consumers can be aware of what “type” of water they are drinking.
But are any of these waters “better” than the rest? Doctors and researchers are still investigating potential health benefits.
Hydrogen Water Shows Promising Results
In the western world, municipal water suppliers have to meet stringent levels of purity and quality for potable water. Despite well-publicized cases where such standards were not met (such as the water crisis in Flint, Michigan), the tap water in most places in America or Europe should be perfectly safe.
The US Academy of Nutrition and Dietetics says there is little evidence supporting or refuting the claimed health benefits of alkaline water.
Commercial operators, eager to make a profit, publicize health claims for their products. In recent years, the bottled water most promoted by influencers and celebrities has been alkaline water, whose pH has been raised (through additives or by picking up minerals naturally) above neutral 7 to around 8 or 9. For a healthy human, blood pH is neutral, and the liver and kidneys do a good job of keeping it that way. People with diabetes can have slightly acidic blood while kidney disorders can cause alkalinity. But according to Melina Malkani, spokeswoman for the US Academy of Nutrition and Dietetics, there is little evidence supporting or refuting the claimed health benefits of alkaline water.
Debunking Distilled Water Concerns: Not as Bad as Previously Assumed
Beyond “healthy” water, there are also persistent beliefs that some kinds of water can be unhealthy. For example, distilled water is claimed to absorb carbon dioxide from the air, leach essential minerals from the body when consumed, and reduce nutrient levels in vegetables when used for cooking. Each of these claims is false.
However, because distilled water contains very low, even negligible, levels of minerals, it is also not a source of nutrition. This is not a serious problem since most people get their nutrients from food, not water. Distilled water tends to taste “flat,” but otherwise is perfectly healthy to drink.
Drink Water. (Almost) Any Water.
In summary, with the exception of the potentially beneficial hydrogen water, it doesn’t really matter what sort of water you drink. The key is simply to drink enough water. As long as you live in an area where the municipal water supply is free from contaminants, the most cost-effective way to stay hydrated is just to turn on your kitchen tap and glug away. You save money, avoid polluting the planet with bottles, and enjoy the life-sustaining benefits that water provides.
*Stuart Nathan is a London-based freelance science writer, specializing in science, engineering, and technology.