The human body consists of up to 60% of water [1]. Naturally, this means you have to drink a lot of fluids to stay well-hydrated and healthy – especially now in the summer heat. But how much do you need to drink daily? And what should you drink to be healthy? Does coffee dehydrate the body and what does this have to do with the environment?
The health benefit of drinking plain water
Water is essential for many processes in the human body: It is needed by the metabolic system for digestion, to flush out bacteria from the kidneys or regulate body temperature. It is also used to cushion joints and even to normalize blood pressure and stabilize the heart beat [3]. And even your skin can benefit from you drinking more water [5]!
Water is therefore essential for all parts of the human body. Only with sufficient hydration are we able to achieve our full potential when working on exhausting tasks and also mental challenges – even the brain needs water!
How much water do you need to drink daily?
It is impossible to make a general statement of how much you need to drink a day: It depends on many factors. Your environment and temperature will affect your fluid needs, just as any medication and your level of activity will. But part of your daily intake is also covered by food, which always contains water as well. As a general rule of thumb, 4-6 cups a day may be helpful.
The best advice certainly is to listen to your body: Thirst will let you know when you need to drink. Once you feel dizzy, confused and weak, you might already be dehydrated.
And behold, hydro homies: For many years, urban myths have promoted that an average adult should drink at least two liters a day [2]. This was debunked as a marketing strategy some time ago. Drinking coffee and tea is regarded to dehydrate you, but this also has been debunked [3]: Any water you are consuming will be used by your body. But coffee will make you need to pee because the caffeine has a diuretic effect on the kidneys [6]. In high doses, this can lead to dehydration.
How to lose weight by drinking water
Drinking plain water has the best benefits for your body: Especially if you are watching your body weight, drinking water can lower your overall energy intake: A recent study [4] showed that those individuals drinking more water had lower energy intake in general. By drinking more plain water instead of sweetened drinks, the resulting lower energy intake can lead to significant weight loss.
Sweet drinks can provide useful hydration for the body, but they will also provide you with energy that you need to burn afterwards – without making you feel full. These additional calories can add up significantly and can cause weight gains. And even worse, the sugar will raise your blood sugar level for a short time and will cause cravings after a while, when the blood sugar drops again. This makes you want to eat even more than you otherwise would.
Water does not raise the blood sugar at all and can therefore help to regulate the blood sugar level. This is important for diabetics as for anyone watching their body weight: With a flat sugar level curve, cravings are also reduced.
Is tap water or bottled water better?
Drinking tap water has many advantages over bottled water: It is readily available in your house without the need to shop and carry it home. It is much cheaper and typically well-controlled to ensure water quality. While microplastics can be found both in tap and bottled water [12], especially chemical pollutants that act as endocrine disruptors can be found mainly in plastic-bottled waters [13]. In addition, the microbial quality of bottled water has been shown to decrease during storage time [14]. And finally from the environmental point of view, bottled water is much more harmful due to CO2 emission during transportation and the generated plastic waste.
Where is tap water safe to drink?
In the following European and other tourist-relevant international countries, tap water is perfectly safe to drink:
- Andorra
- Austria
- Belgium
- Canada
- Croatia
- Czech Republic
- Denmark
- Estonia
- Finland
- France
- Germany
- Gibraltar
- Greenland
- Iceland
- Italy
- Ireland
- Liechtenstein
- Lithuania
- Luxembourg
- Macedonia
- Malta
- The Netherlands
- New Zealand
- Norway
- Poland
- Portugal
- San Marino
- Singapore
- Slovakia
- Slovenia
- Sweden
- Switzerland
- The United Kingdom
In some countries, tap water is safe in the major cities but might be problematic elsewhere. Among these are:
- Australia
- Bosnia and Herzegovina
- Bulgaria
- Colombia
- Greece
- Hungary
- Romania
- Serbia
- Spain
In some countries, tap water should be avoided, such as:
- Albania
- Belarus
- Monaco
- Montenegro
- Ukraine
Information about safety of tap water was collected from [7], [8] and [9].
Is tap water still safe to drink during the Corona virus pandemic?
Yes, tap water is still safe to drink even in this special situation. According to the WHO, no traces of the COVID-19 inducing (or other Corona-type) virus have been found in water supplies [10]. In general, drinking water is treated for pathogens such as viruses so that they don’t pose a thread to water supplies [11].
I was a big fan of tap water before and still am. In the last few years I have lived in places where I did not like the taste of the water and had to use a water filter to enjoy it. But still I never relied on bottled water for a longer time because I want to minimize the environmental impact of my fluid supply. Do you prefer bottled or tap water – and why is that?
References:
[1] https://www.usgs.gov/special-topic/water-science-school/science/water-you-water-and-human-body
[2] https://www.cbc.ca/news/health/8-glasses-of-water-a-day-an-urban-myth-1.1196386
[3] https://www.health.harvard.edu/staying-healthy/how-much-water-should-you-drink
[4] https://onlinelibrary.wiley.com/doi/abs/10.1111/jhn.12368
[5] https://www.uwhealth.org/madison-plastic-surgery/the-benefits-of-drinking-water-for-your-skin/26334
[6] https://pubmed.ncbi.nlm.nih.gov/27225921/
[7] https://www.tripsavvy.com/the-worlds-cleanest-tap-water-4159592
[8] https://www.tripsavvy.com/tap-water-in-europe-3150039
[9] https://www.thewaterdeliverycompany.com/2018/03/12/countries-best-drinking-water/
[10] https://www.who.int/publications/i/item/water-sanitation-hygiene-and-waste-management-for-covid-19
[11] https://www.epa.gov/coronavirus/drinking-tap-water-safe
[12] https://www.who.int/water_sanitation_health/publications/microplastics-in-drinking-water/en/
[13] https://www.sciencedirect.com/science/article/pii/S0960076010003572
[14] https://www.sciencedirect.com/science/article/pii/S2215016119300123
