Water Sources

Common sources of water for human consumption are tap water, bottled water, other beverages and water-containing foods. Apart from that, some “metabolic water” is produced in the human body during breakdown of carbohydrates, proteins and fats (Chart 1).

Chart 1. Sources of Water
WATER SOURCE	AVERAGE WATER GAIN/DAY in 19-30 years old adults in the U.S. [3]
Beverages	2,200-3,000 mL
Foods	~700 mL
Metabolic water [12,30]: 1 g fat yields 1.07 g water 1 g carbohydrates yields 0.6 g water 1 g protein yields 0.4 g water	Sedentary person: 300 mL Physically active person: up to ~600 mL
TOTAL WATER GAIN	3,200-4,300 mL per day

Chart 1 sources: ^[2,3]

Chart 3. Foods With High Water Content

150-220 mL WATER PER CUP (1 cup = 237 mL)

Fruits: horned melon, grapefruit, lemon, soursop, passion-fruit, pummelo (pomelo), tangerine, orange, breadfruit, litchis

Vegetables: pumpkin, spinach, squash (winter, summer), collards, cauliflower, tomatoes, broccoli, cabbage, Swiss chard, rutabagas, asparagus

Cooked cereals: teff, amaranth

Other: yogurt, popsicles

100-150 mL WATER PER CUP

Fruits: kiwifruit, melon (cantaloupe), plums, pineapple, watermelon, berries, peach, apricot, persimmon, guava, papaya, cherimoya, nectarine, grapes, jackfruit, carambola, sapote, avocado, cherries, banana, rhubarb

Vegetables: chayote, kohlrabi, turnips, turnip greens, potatoes, artichokes, beets, celery, mustard greens, gourd, bamboo shoots, carrots, Brussels sprouts, taro leaves, garden cress, kale, leeks, salsify, purslane

Cooked cereals: rice, oatmeal, cornmeal, bulgur, quinoa, buckwheat, noodles, couscous, noodles, barley, sweet corn; 80-100 mL water: pasta: macaroni, spaghetti

Other: pudding

Chart 3 source: ^[2]

NOTE:

• Apples, pears and mangoes and their juices are high in fructose, which may trigger diarrhea when consumed in high amounts.
• Beans, peas, lentils, barley and oats are high in soluble fiber that can bind a lot of water in the intestine; they can also cause excessive gas.
• Chocolate, candies, crackers, nuts and seeds usually contain less than 10%, and bread contains about 40% water. Meats, fish and cheese can contain more than 50% of water but they are not good water sources because they are high in protein, which stimulates water excretion by urine.

Types of Drinking Water

Drinking or potable water is water that is clean enough to be used for human consumption. Pure drinking water has no color. Tap water usually has some taste and chlorinated tap water may have a chlorine smell. The taste of mineral water depends on the mineral content. The amount of salt in the typical municipal water in the United States is lower than 100 mg per liter and is restricted to 500 mg per liter; the restriction for drinking water in general is 1,000 mg (1 g) per liter ^[7].

Types of Drinking Water by SOURCE:

Ground water is water from subsurface that is not in the direct contact with surface water ^[8]. In general, ground water has less microbes than surface water, but is not microbe-free ^[9]. The mineral content, hardness, acidity and amount of pollutants in ground water may vary a lot from area to area and can be corrected by water treatment systems before used as a drinking water.

Spring water is derived from the spring, where underground water flows naturally to the surface of the earth ^[8]. Unprotected spring water is often contaminated by bacteria and may not be safe to drink ^[10]. Spring water, after treating, can be used as a municipal or bottled water.

Well water is water from a well that taps an underground aquifer ^[8].

• Information about wells from the US Environmental Protection Agency (EPA.gov)
• Information for well owners in the U.S., state by state

Artesian water is ground water that is under pressure when tapped by a well ^[8].

Rainwater is harvested from rain. It contains very little minerals but is not mineral-free, like distilled water ^[27].

Tap water, also called running water, city water or municipal water originates from the ground or spring water or other surface water, such as a lake or even sea, and is conducted to households via municipal water systems.

Snow is frozen rain. Like rainwater, it contains very few minerals ─ most of them are from air pollution ^[34]. NOTE: When you intend to eat snow to prevent dehydration, you should melt it before use, if possible. Eating snow without melting can cause dangerous decrease of your body temperature (hypothermia).

Bottled Water

Bottled water, by definition, contains only water without added substances, except disinfectants and, sometimes, fluoride ^[8]. Bottled waters usually contain less fluoride than fluoridated tap water, but fluoride may be added to certain bottled waters in amounts up to 1.7 mg fluoride per liter ^[8].

The source of bottled water may be ground water, spring water or municipal water. More specific sources can be mentioned on the bottle labels: “artesian water”, “well water”, “mountain water”, “glacier water” and so on.

Bottled Water Safety

In the U.S., the content of bottled water is regulated by the Food and Drug Administration (FDA) ^[8]. National Sanitation Foundation (NSF) ^[13], some other organisations and some state health departments certificate bottle waters. Bottled waters in the U.S. are usually purified, which means certain substances, but not necessary all microbes, have been removed from them ^[28].

• Bottled waters disinfected by ozone, ultraviolet light or chlorine dioxide, as well as distilled water, and water treated by reverse osmosis should be free of most microbes, including Cryptosporidium ^[11]. Sterile water should be free of all detectable microbes ^[11]. An “absolute one micron” filtered water should not contain the parasite Cryptosporidium, but may contain bacteria or viruses ^[11].
• Amount of potentially toxic chemicals and heavy metals allowed in bottled water is regulated by the US Food and Dug Administration ^[8]. Bottled water can contain antimony, arsenic, benzene, beryllium, cadmium, chlorine, copper, cyanide, dioxin, lead, mercury, nickel, nitrates, PCB, thallium, trihalomethanes, vinyl chloride or other contaminants in minute amounts that should not be harmful for health ^[8].
• PET (polyethylene terephthalate) bottles may be safely used as plastics intended for use in contact with food, according to the US Food and Drug Administration (FDA) ^[41]. In one 2012 study, during exposure of deionized water stored in PET bottles from Britain and Nigeria at 60° C for 48 hours, the amount of antimony leached from the bottles to water was within the EU acceptable limits ^[42]. Antimony has not been proven as a cancer-causing substance in humans ^[44].

Why some bottled waters have an expiration date? Bottled water is considered to have an indefinite safety shelf life, but the taste or smell of water can change over time–more in plastic than in glass bottles–, so this is why some producers put expiration dates on the labels ^[21]. Many health professionals recommend using opened bottled water for up to 2 weeks at most because bacteria can multiply in it; the water may last longer if you keep it in the refrigerator.

Can leaving a bottled water in a hot car result in leaching cancer-causing (carcinogenic) toxins, such as dioxin, from the bottle plastic into the water? In the US, the plastic used for water bottles is regulated by FDA, and should not affect health-related characteristics of water, when used or stored in common places including hot cars ^[40]. Most plastic bottles for water are made of PET (polyethylene terephthalate), which cannot produce dioxin even after heating or burning ^[43].

Mineral Water

Mineral water, by the definition in the U.S., is water naturally containing at least 250 milligrams per liter of dissolved solids (minerals), and originating from physically protected underground water ^[8]. Mineral water containing less than 500 mL/L solids is labeled as “low mineral content” and water containing more than 1,500 mg/L as “high mineral content” ^[8].

Possible health benefits of mineral water. Mineral water can be an important source of calcium and magnesium for individuals who do not get enough of these minerals from foods. Note that tap water in some areas is also high in calcium and magnesium. There is insufficient evidence about beneficial or harmful effects of drinking mineral water and its calcium, magnesium or sodium content on health ^[37,38].

Purified Water:

Purified water is water that was distilled, deionized or treated with reverse osmosis. It contains no more than 10 parts per million (ppm) or 10 mg/liter of solids and contain less microbes than non-purified water, but is not necessary microbe-free ^[11].

Deionized or Demineralized Water

Deionized (DI) water, also known as demineralized water is water from which almost all ions or minerals have been removed by ion exchange, electrodialysis or reverse osmosis ^[29]. Note that deionized water may still contain organic impurities and microbes. Deionizing household water systems and deionized bottled water are available.

In reverse osmosis, applied pressure pushes water through a membrane that is permeable for clear water, but not for most dissolved substances and thus removes 80-99% of minerals (arsenic, aluminum, barium, beryllium, cadmium, calcium, chloride, chromium, copper, fluoride, iron, lead, magnesium, manganese, mercury, nitrate, potassium, radium, selenium, silver, sodium, sulfate, and zinc) and parasites but not necessary bacteria and viruses ^[26,35].

Distilled Water

During distillation, salt water is heated and then clear vaporized water without minerals collected. Distillation removes all minerals, including sodium, calcium and magnesium (water hardness), nitrates and other non-volatile compounds, some pesticides, parasites, bacteria and viruses; it does not remove volatile compounds that have lower boiling point than water, for example, benzene and toluene ^[29,36].

Household water distillers remove minerals (calcium, magnesium, sodium, fluoride), heavy metals (arsenic, lead, mercury), radioactive elements (radium, radon), asbestos, benzene, nitrates, trichloroethylene (TCE), trihalomethanes, microbes and certain herbicides from water ^[11,14]. Household distillers may not remove volatile compounds, such as certain pesticides, chlorine and radon.

Distilled bottled waters are sold in some markets.

Is distilled or deionized water safe to drink? Distilled water has no minerals, but when drunk, it mixes with minerals from food and pancreatic juice and hydrochloric acid in the stomach.

According to one human trial performed by World Health Organization (WHO) in 1980 ^[4], long-term consumption of purified water (deionized or distilled water) may cause increased water excretion from the body through urination (diuresis) by about 20% and increased excretion of sodium, potassium, calcium and magnesium possibly resulting in tiredness, weakness, muscular cramps and cardiovascular disorders, but there is a lack of other studies that would confirm this.

Sterile or Sterilized Bottled Water

Only bottled water that is labeled as “sterile” and certified according to FDA requirements by independent institution, such as NSF, is considered microbe-free ^[11,15]. Bottled waters that are “filtered”, “purified”, “deionized” or “demineralized” are not already sterile. Even bottled water that were “distilled” or “treated by reverse osmosis” and which do not likely contain measurable amounts of microbes, are officially not sterile, unless certified as such. This means most bottled waters on the market are officially not sterile.

Sterile bottled water is intended for preparation of formula for infants younger than three months ^[16] and individuals with weak immune system due to genetic disorders, AIDS, chemotherapy, transplantation or other cause ^[11].

Soft Drinks

Carbonated water also called soda water, club soda, fizzy water and seltzer water contain added carbon dioxide. Sparkling bottled water contains the same amount of either naturally present or added carbon dioxide as it had at emergence from the source ^[8]. The beforementioned waters, vitamin water and flavored water are considered soft drinks and are not regulated as bottled waters ^[8,11].

Water From Wild Plants

How can you obtain water from wild plants ^[19]:

• Coconut water from an unripe (green) coconut. Make a hole in a coconut, and another hole to allow the air to enter and drink the water. Water from ripe coconuts contains oils that may have a laxative effect, so drink in moderation.
• Green bamboo thickets. Cut the top of the green bamboo and bend it down and let the water to drop from it overnight.
• Banana or plantain tree, sugarcane. Cut the tree about 14 inches (30 cm) from the ground and cut out some pulp from the center to create a bowl. The water, which will come up from the roots, may suffice for up to four days.
• Traveler’s tree in Madagascar collects water on the leaves.

Barrel cactus does not necessary contain a lot of water, which may also be alkaline and can make you vomit ^[1].

Inappropriate Sources of Water

Surface Freshwater Sources

Drinking water from rivers, streams, lakes and geysers, which are often contaminated with microbes, may result in gastrointestinal infection and diarrhea, from which you may lose more water than you have consumed. The more upstream you go, the less likely the water will be contaminated, but even springs are not absolutely clean. Water disinfection by boiling or other methods kills microbes but does not destroy all other pollutants. Always weigh the risk of infection or poisoning and the risk of death from dehydration before you drink water from these sources.

Why is drinking seawater not good? By drinking one liter of seawater, you consume about 35 grams of sodium chloride. In order to excrete 35 g of this excessive sodium chloride (plus other solutes that need to be excreted), your kidneys need to excrete at least about 1.5 liters of urine, which means that after drinking 1 liter of seawater you will lose about 1.5 liters of water from your body, which is 0.5 liters of net water loss ^[19,20,45].

Brackish water is a mixture of fresh water from rivers and seawater. It can contain 1-10 g of salt per liter ^[31]. Brackish water is one of the most polluted waters so even if it contains much less salt than sea water is not safe to drink.

NOTE: Sea ice and ice from icebergs are usually appropriate sources of drinking water. Crystalline sea ice, which forms on the sea surface, contains about 10 g of salt (4 g sodium) per liter so a drinking water can be obtained from it by melting ^[32,33]. Grey or opaque sea ice contains a lot of salt and can be made into drinking water only after melting and desalinating ^[19]. Icebergs, which are blocks of freshwater ice that has broken from a glacier and is floating freely in the sea, can be used as a source of drinking water ^[33]. WARNING: Eating non melted ice when you are in a cold ambient can result in hypothermia and increased urination and thus water loss due to cold diuresis, so it is not recommended to quench thirst.

Urine

Urine drinking does not seem to be an efficient method for prevention or treatment of dehydration ^[19]. When you are already dehydrated, your urine, which will likely be yellow or brown, will contain a lot of urea–a breakdown product of protein metabolism–, so when you drink such an urine, your kidneys will need to excrete quite some water to be able to excrete urea and your net water gain will be minimal or even negative. When you are still well hydrated but you expect to become dehydrated and you drink urine, your body will detect this as a fluid overload any you will excrete most of the consumed urine within few hours. If you store the urine for later, the bacteria in urine will multiply and, after drinking, possibly cause gastrointestinal infection with diarrhea, from which you can lose more water than the urine you have drunk contained.