The World's Healthiest Foods are health-promoting foods that can change your life.

Try the exciting new lunch recipe from Day 4 of our upcoming 7-Day Meal Plan.

The George Mateljan Foundation is a not-for-profit foundation with no commercial interests or
advertising. Our mission is to help you eat and cook the healthiest way for optimal health.
Can you tell me more about water and why drinking it is so important to our health?


Natural, clean water is virtually crystal clear, and contrary to popular opinion, it has its own unique taste. This taste is not the taste found in ordinary tap water, although many people have become so accustomed to tap water that they cannot distinguish it as having any particular "taste." The chlorine added to municipal tap waters is probably the greatest single contributor to tap water taste, but unless you've had several weeks to adjust to natural water with most of the chlorine filtered out, you may not be able to tell any difference between chlorinated and filtered.

Most of the water that we drink comes from groundwater below the soil that is pumped up and in many cases processed. In science terms, there is a cycle called the hydrology cycle, and this cycle tells the story of natural water. Water arrives at the earth in the form of rain or snow or ice, and it can run off of mountains and hills, or through rivers and streams, down to the ocean. It can also percolate straight down through the soil into groundwater. This passage of water downward through the soil is great for mineralization of water, but it is problematic because we have polluted the soil with garbage and waste in the form of landfills or toxic waste dumps.

Nutritional Profile

Due to the enormous variation in drinking water quality, it is impossible to provide any helpful nutrient profile for "water" per se. Many city tap waters will contain less than 5 milligrams of calcium per cup, less than 2 milligrams of magnesium, and only trace amounts of other minerals. As described earlier, some high-quality mineral waters will provide over 25 milligrams of magnesium per cup, over 35 milligrams of calcium, and small amounts of more than a dozen additional minerals. Pure, natural water does not contain protein, fat, carbohydrate or fiber. It is also calorie-free.

Health Benefits

Many scientists credit water as being the reason for life on earth. All creatures on earth—including humans—rely on water more than any other substance to stay healthy. We can go longer without food than water, and virtually all of our other nutrient requirements are impacted by the amount of water we drink. The reason is simple: our bodies are about 60% water by weight, and most nutrients move around through our body in water. Our bloodstream is composed primarily of water, and so are all of our tissues and organ systems. Water is also the key to elimination of toxins from our body (in the form of urine and perspiration). There isn't a single bodily function—from seeing and hearing and thinking to running and singing and laughing—that does not depend on water.

Exactly how helpful is water to our health? Researchers at Loma Linda University looked at water consumption in a group of more than 20,000 men and women in their Adventist Health Study. In this study, they determined that adults drinking 5 or more glass of water each day were about 50% less likely to die from a heart attack. They made some other comparisons involving water and health, and in their announcement of the results, these researchers ranked increased water drinking equal very close to smoking cessation in terms of heart health! Other research has shown that water drinking helps maintain proper blood pressure, improves mental performance, increases athletic performance, and helps regulate digestion.

It's helpful to think about the health benefits of water in three basic categories. First is the fluid aspect of water. Water is a lubricant. It keeps things flowing and moving. While it lubricates, water also protects our body parts from damage by surrounding them in a shock-absorbing fluid. This aspect of water is especially important in our joints, and also in our skin. The second aspect of water is its role as a "solvent." Most nutrients dissolve in water. In our bodies, some of the most important dissolved nutrients are called "electrolytes." The electrolyte minerals like potassium and sodium stay dissolved in water, and the ability of water to dissolve electrolytes is a key reason why our bodies can conduct electricity. The third aspect of water involves its role as a thermostat. When we are too hot, water lets us shed heat through sweating. Water also helps us retain heat when we need to stay warm.

As mentioned earlier, the minerals in naturally formed water are indispensable to our health. Most people are not aware of the research in this area. Well-conducted studies in Sweden and in Poland have shown that the risk of heart disease, especially in men, could be substantially reduced if more natural water (like the type of well-water found in rural areas) were consumed. All of these studies focused on the mineral magnesium. Most of the city water in these countries—and in the United States—is very low in magnesium in comparison to the amount of magnesium found in water that has percolated down through the earth's natural watersheds and soils and been allowed to pick up magnesium and other minerals in this way. One glass of tap water in most cities throughout the U.S. will contain about 0-2 milligrams of magnesium. By comparison, one glass of mineral water (like the bottled mineral waters purchased in a grocery store) will contain about 2-5 milligrams of magnesium, and some bottled mineral waters will contain over 25 milligrams per cup! Even though the magnesium in one cup of mineral water might seem small, it can add up very rapidly. The adult requirement for magnesium ranges from 320-420 milligrams per day. Four cups of mineral could provide about 25-30% of this amount each day while eight cups could provide over half of the daily requirement! These numbers make water equivalent to a food like Swiss chard in terms of its magnesium content. And all of these health benefits come in exchange for zero calories.

Contaminants in Water and the Importance of Filtration

Virtually all city water supplies in the United States show dozens of different toxic residues, including pesticides, heavy metals, and solvents. A significant number of water supplies are routinely out of compliance with the federal standards and take steps to bring their toxic residues back into acceptable ranges. Over 1,000 potential toxic residues have been identified in drinking waters across the country, and about 300 are routinely tested by the federal government to determine exact toxin levels. To give an example of the widespread nature of this problem, the pesticide atrazine was found to be present in 96% of 374 community water supplies in 12 states surveyed in 2001 by the Environmental Working Group in Washington, D.C.

The range of potential contaminants in drinking water is somewhat surprising when you first encounter it. Inorganic chemicals (like mercury), organic chemicals (including solvents like toluene, pesticides like atrazine, and plastics like PVC), disinfectants (like chlorine bleach), microorganisms (like coliform bacteria), and even radionucleotides (like radium or uranium) can be found in many drinking water supplies in the U.S. and throughout the world. In the U.S., the Environmental Protection Agency (EPA) monitors toxin levels in our drinking water, and maximum allowable contamination levels (or MCLs) are set for approximately 80 of the 100's of potential substances involved. Major factors in the contamination of our drinking water are sewage sludge disposal (and fertilizers that can contain residues of sewage sludge), hazardous landfills, and industry pollution of lakes and streams.

Due to the almost universal risk of toxic residues, filtering of water is important. There are ways to filter water properly at home, and there are a large number of high-quality filtered waters in the marketplace.

There are two basic styles of filtering. The first style involves your faucet. Water filters that can be placed at or near your faucet are called POU (or point-of-use) filters. The second style of filtering is POE (or point-of-entry) filtering, where you place the filter in a more central location to impact all of the water flowing into your house. Many people cannot afford the cost of POE filters that filter all of the water flowing into their home, and for this reason, select POU filters that only affect a single faucet.

We believe that faucet-level filtering can be very effecting for producing healthy drinking water, but we like the research on under-the-sink filters much better than the research on filters that attach directly at the end of the faucet. One of the major differences we see here involves the use of solid carbon blocks in the under-the-sink filters versus granulated carbon particles in the end-of-the-faucet filters. Granulated carbon does not show the same effectiveness in research for filtering potential toxins as solid block carbon.

Carbon water filters are fairly effective at removing many organic chemicals and chlorine, but they are not necessarily perfect for bacteria or for heavy metals. You can increase your chances of having water that is free of unwanted microorganisms by selecting a carbon block filter that has a very low micron rating. Micron rating refers to the size of the openings in the filter. In general, we recommend filters that have a micron rating no greater than 1 micrometer.

Bottled Water

In general, most of the bottled spring waters, mineral waters, and carbonated mineral waters on the market are sufficiently high-quality and properly filtered. However, we would recommend that you pay attention to three details when purchasing water. First, we do not recommend water that is packaged in plastic—even the hard polycarbonate plastic that is popular in 5-gallon jugs that can be taken home and used with a water stand.

The reason for our recommendation is migration of plastic. Even at room temperature, a very small amount of the plastic in the water container will migrate into the water and increase certain health risks. In some cases, the degree of risk here is very, very small, Nevertheless, since we drink (or should be drinking) water every single day of every single year, any amount of risk here seems worth preventing. Even though glass containers are very inconvenient and more easily broken, we believe that the additional trouble here is worthwhile in terms of health.

The second detail when selecting bottled water is the source. Virtually all high-quality bottle water will identify the source of the water on the bottle. It's important to ignore the brand name here and focus on the information provided to you on the bottle. Many waters sounding natural and healthy came from a city water supply in the United States that was not high quality. If you cannot easily find a water that tells you its source, your next best step is to make sure that the water has been filtered by looking on the bottle's ingredient list to see it the list says "filtered water." But it's much better to purchase a water that indicates the source of the water, and the reason that this source is desirable.

The third detail deserving attention is dissolved solids. As described earlier, mineral waters have the important advantage of providing calcium magnesium, and other essential minerals that are often deficient in our food. Some bottled waters list these minerals and their amounts on the label, but most do not. If the mineral content of a water is not specified, the bottle might still indicate "total dissolved solids" in parts per million, or ppm. A level above 1,000 ppm is a very reasonable starting point here, and a level above 1,500 ppm indicates a highly mineralized water. It's very important to have a high-quality water that is free of toxic residues when purchasing a highly mineralized water because "total dissolved solids" could include unwanted minerals and other substances in the case of a low-quality water. While we don't like to recommend specific brand names on our website, we've found many commonly available bottled minerals waters that are high quality according to the principles above.

Best Ways to Drink Water

We recommend that water be consumed in large volumes (one cup or greater) between meals rather than at meal times. Although there is not sufficient research to document the potential problems with water during meals, we've read many healthcare providers report better food digestion in the stomach, better appetite, and better overall digestive health from limited water drinking during meals. Many hypotheses about the impact of water during meals can be found in the research literature, including hypotheses about dilution of stomach acid and consistency of food as it passes through the digestive tract. Without good research support, however, these hypotheses are only hypotheses, and our recommendation is based on informal reports by healthcare providers who focus on diet and health.

Although there are many healthy and natural flavorings that can be added to water—including lemon juice, lime juice, and pre-mixed vitamin/mineral packets—there is an important role to be played by pure, natural water. Some people report better digestive function with lemon juice added to water, and that practice may be preferable in some cases, even though we have not seen any research in this area. In general, however, too many children and adults throughout the U.S. never consume plain, simple water, and from our perspective, it's important to develop a taste for water all by itself.

Cold water can be more quickly absorbed from the stomach than hot water, and for this reason, there are times when cold water is helpful for quick rehydration. After a gym workout, for example, many people prefer water at a cold temperature. However, there are definitely exceptions, and for some individuals it is far easier to consume a substantial amount of water at room temperature than the same amount on ice or refrigerated.

One of the biggest questions about water drinking is amount. This question is a matter of ongoing debate, both in the media and in the research world. However, there are several general guidelines that we would like to emphasize in this context. The first is that although it's possible to drink too much water, it's highly unlikely that you will do so! "Water intoxication"—as it's commonly called in the medical world—usually involves imbalance in some of the body's physiological systems and not just excessive intake of water. We give you the "green light" to drink as much water as you desire, provided that you stick with the natural and high-quality principles that we have described.


  • Brewster D. Dehydration in acute gastroenteritis. J Paediatr Child Health. 2002 Sep;38(3)219-22. 2002. PMID:12047685.
  • Chan J, Knutsen SF, Blix GG, et al. Water, other fluids, and fatal coronary heart disease: the Adventist Health Study. Am J Epidemiol. 2002 May;155(9)827-33. 2002. PMID:11978586.
  • Environmental Working Group. Tough to swallow: how pesticide companies profit from poisoning America's tap water. 1997.
  • Iggulden H. Dehydration and electrolyte disturbance. Elder Care. 1999 Nov;11(3)17-22; quiz 23. 1999. PMID:10542527.
  • Rubenowitz E, Axelsson G, Rylander R. Magnesium in drinking water and death from acute myocardial infarction. Am J Epidemiol. 1996 Mar;143(5)456-62. 1996. PMID:8610660.
  • Rubenowitz E, Molin I, Axelsson G, et al. Magnesium in drinking water in relation to morbidity and mortality from acute myocardial infarction. Epidemiology. 2001 Feb;11(4)416-21. 2001. PMID:10874548.
  • Rylander R, Bonevik H, Rubenowitz E. Magnesium and calcium in drinking water and cardiovascular mortality. Scand J Work Environ Health. 1991 Apr;17(2)91-4. 1991. PMID:2047817.
  • Sheehy CM, Perry PA, Cromwell SL. Dehydration: biological considerations, age-related changes, and risk factors in older adults. Biol Res Nurs. 2001 Mar;1(1)30-7. 2001. PMID:11225294.
  • United States Environmental Protection Agency. National water quality inventory: 1998 report to Congress. EPA 841-R-00-001. 1998.
  • United States Environmental Protection Agency. Office of Water. Estimated per capita water ingestion in the United States. EPA 822-R-00-008. 2000.

Printer friendly version

Send this page to a friend...


Newsletter SignUp

Your Email:

Find Out What Foods You Should Eat This Week

Also find out about the recipe, nutrient and hot topic of the week on our home page.


Everything you want to know about healthy eating and cooking from our new book.
2nd Edition
Order this Incredible 2nd Edition at the same low price of $39.95 and also get 2 FREE gifts valued at $51.95. Read more

Healthy Eating
Healthy Cooking
Nutrients from Food
Website Articles
Privacy Policy and Visitor Agreement
For education only, consult a healthcare practitioner for any health problems.

We're Number 1
in the World!

35 million visitors per year.
The World's Healthiest Foods website is a leading source of information and expert on the Healthiest Way of Eating and Cooking. It's one of the most visited website on the internet when it comes to "Healthiest Foods" and "Healthiest Recipes" and comes up #1 on a Google search for these phrases.

Over 100 Quick &
Easy Recipes

Our Recipe Assistant will help you find the recipe that suits your personal needs. The majority of recipes we offer can be both prepared and cooked in 20 minutes or less from start to finish; a whole meal can be prepared in 30 minutes. A number of them can also be prepared ahead of time and enjoyed later.

World's Healthiest
is expanded

What's in our new book:
  • 180 more pages
  • Smart Menu
  • Nutrient-Rich Cooking
  • 300 New Recipes
  • New Nutrient Articles and Profiles
  • New Photos and Design
privacy policy and visitor agreement | who we are | site map | what's new
For education only, consult a healthcare practitioner for any health problems.
© 2001-2017 The George Mateljan Foundation, All Rights Reserved