The Pure Water Occasional for June 15, 2015
In this almost summer Occasional, you’ll hear a lot about drought and flooding from Texas to California, plus lead contamination in Ireland, the decline of the Joshua tree, and water recycling in Singapore. Then there are artificial sweeteners, artificial turf, and artificial diabetes. Failure of an inflatable dam, nuclear waste near Lake Huron, Nestle’s “zero water” plants, the “Waters of the U.S. Rule,” and changes in historic water rights in California. A lot about food and water, new irrigation strategies, the thirstiest crops, why flooding rice fields isn’t so bad, and the tons of animal manure that threaten water supplies. Perchlorate in Haliburton’s home town, cysts in drinking water, World Oceans Day, a revisitation of the eternal question of how much water we should drink, and, as always, there is much, much more.
To read this issue on the Pure Water Gazette’s website, please go here. (Recommended! When you read online you get the added advantage of the Gazette’s sidebar feed of the very latest world water news.)
Rivers, lakes loaded with artificial sweeteners
It may be lurking in your diet soda, your chewing gum and even in your favorite yogurt. Now scientists have found artificial sweeteners are also coming out of your faucet. Sweeteners are used in thousands of food and beverages sold around the world, according to The Sugar Association. And on World Oceans Day, marked every June 8, scientists are asking us to consider where sweeteners end up after they’re ingested. According to recent research, scientists have found artificial sweeteners in bodies of water around the world, including Canada.
Sugar substitutes — such as Splenda and Sweet’N Low — are designed to be eaten, but not absorbed by the body. Because our bodies cannot break them down, sweeteners go straight through humans.
That’s how consumers get the sweet taste without the weight gain often associated with sugar-laden foods.
Once the sweetener leaves the body, wastewater treatment plants face the same dilemma: studies have found they can’t break down the complex chemical. Most sweeteners, then, flow into oceans, lakes and rivers in practically the same form in which they were consumed.
It’s a situation playing out in the water flowing through southwestern Ontario’s Grand River, which empties into Lake Erie. Researchers from the University of Waterloo and Environment Canada found the amount of sugar substitute in the water is equivalent to about 81,000 to 190,000 cans of artificially sweetened soda flowing through the 300-kilometre river each day.
The study tested for sucralose, cyclamate, saccharin and acesulfame. It also found three types of sweetener coming out of the faucets in Brantford.
Sweeteners could harm aquatic life
According to the Canadian study, the effect of artificial sweeteners in the water is largely unknown. But Amy Parente, an assistant professor of biochemistry at Mercyhurst University in Erie, Penn., says scientists should be on alert.
Parente did her own study in Lake Erie looking for sucralose, the substitute used by Splenda. Her team also found the sweetener in the water. But while other studies took samples from what came out of wastewater treatment plants, Parente tested water found at the lake’s beaches, where the sweeteners had a chance to dilute.
She and her team found 0.15 micrograms of the sweetener for every litre of water, which meant there could be up to 72 metric tons of sweetener floating in the waters of Lake Erie.
Since Parente’s study came out in 2012, Parente and her students have been looking at how sweetener affects a snail living in Lake Erie that forages for food. As part of that work, one student found the presence of sweetener made the animals believe there was nutrition in the water.
The team believes the sweetener affected their foraging abilities, leaving them with fewer calories to be healthy and reproduce. And Parente thinks this could be true for other foraging animals.
“When people think about small animals and small organisms, they tend not to be concerned,” Parente said in a phone interview with CTVNews.ca. But she added the impact has the potential for a domino effect.
Another study published by Environmental Science and Technology also found large amounts of sucralose, saccharin, aspartame and acesulfame near wastewater treatment plants in New York State. The study suggested sweetener can harm a plant’s ability to perform photosynthesis.
This could create less food for animals that depend on the plants, creating a ripple effect that could make its way back to humans.
The taste is not in the tap
For now, more research is needed before drawing any conclusions about sweeteners’ impact on all aquatic life, said Environment Canada research scientist, John Spoelstra, part of the team that tested the Grand River.
And while research shows a large amount of sugar substitutes in our bodies of water, Spoelstra said consumers shouldn’t expect their drinking water to taste any sweeter.
“Concentrations in the river are very small,” Spoelstra told CTVNews.ca. “They’re in the tens to hundreds of thousands of times lower than the concentration that would be in a can of soda.”
As for aquatic life, scientists have had less than a decade to study the effect of the sweeteners, since research showing its concentration only came out a few years ago, Spoelstra said. But work is underway by scientists around the world.
The few studies that have come out shouldn’t be ignored, Parente said, likening them to the canary in the coal mine.
“I feel that out of these small organisms are early warnings,” she said. “We need to heed those warnings.”
Source: CTV News.
Water Required to Produce These Three Hamburger Patties: 1350 Gallons.
Our Water-Guzzling Food Factory
by Nicholas Kristof
Let’s start with a quiz.
Which consumes the most water?
A) a 10-minute shower.
B) a handful of 10 almonds.
C) a quarterpound hamburger patty.
D) a washing machine load.
The answer? By far, it’s the hamburger patty. The shower might use 25 gallons. The almonds take up almost a gallon each, or close to 10 gallons for the handful. The washing machine uses about 35 gallons per load. And that beef patty, around 450 gallons.
The drought in California hit home when I was backpacking with my daughter there recently on the Pacific Crest Trail, and the first eight creeks or springs we reached were all dry.
The crisis in California is a harbinger of water scarcity in much of the world. And while we associate extravagant water use with swimming pools and verdant lawns, the biggest consumer, by far, is agriculture. In California, 80 percent of water used by humans goes to farming and ranching.
That’s where that hamburger patty comes in.
I grew up on a sheep and cherry farm near Yamhill, Ore. I worked for a year for the Future Farmers of America, and I still spend time every year on our family farm. But while I prize America’s rural heritage, let’s be blunt: It’s time for a fundamental rethinking of America’s food factory.
A mandarin orange consumes 14 gallons of water. A head of lettuce, 12 gallons. A bunch of grapes, 24 gallons. One single walnut, 2 gallons.
Animal products use even more water, mostly because of the need to raise grain or hay to feed the animals. Plant material converts quite inefficiently into animal protein.
So a single egg takes 53 gallons of water to produce. A pound of chicken, 468 gallons. A gallon of milk, 880 gallons. And a pound of beef, 1,800 gallons of water. (Of course, these figures are all approximate, and estimates differ. These are based on data from the Pacific Institute andNational Geographic.)
You can also calculate your own water footprint at National Geographic’s website.
Our industrial food system produces food almost miraculously cheaply. In 1930, whole dressed chicken retailed for $6.48 per pound in today’s currency, according to the National Chicken Council; in real terms, the price has fallen by more than three-quarters. And, boy, is the system good at producing cheap high-fructose corn syrup!
Yet industrial agriculture imposes other unsustainable costs:
• It overuses antibiotics, resulting in dangers to the public from antibiotic-resistant diseases. About four-fifths of antibiotics sold in the United Statesare for livestock and poultry — even as 23,000 people die annually in America from antibiotic resistant infections, according to the Centers for Disease Control and Prevention.
• Farming overuses chemicals such as pesticides, some of them endocrine-disruptors that have been linked to possible cancer, obesity and reproductive disorders.
To this indictment, we can add irrational subsidies and water engineering projects that have led to irrigation in areas where it doesn’t make sense. Today, California, despite the drought, is effectively exporting water (in the form of milk, beef, walnuts and produce).
Most of agriculture’s irrationalities aren’t the fault of farmers but arise from lax regulation and mistaken pricing, and that’s true of water as well. Traditionally in the West, water was mostly allocated on a first-come basis, so if you acquired water rights more than a century ago you can mostly still access water for uses (two gallons per walnut!) that no longer make sense in an age of scarcity.
As for the foolishness of agricultural subsidies, until recently, the federal government paid me, a New York journalist, $588 a year not to grow crops in Oregon. I rest my case.
Let’s be clear that it’s unfair to blame farmers for the present problems. We’re the ones eating those water-intensive hamburgers, and we’re the ones whose political system created these irrationalities.
Like most Americans, I eat meat, but it’s worth thinking hard about the inefficiency in that hamburger patty — and the small lake that has dried up to make it possible.
Maybe our industrial agriculture system is beginning to change, for we’re seeing some signs of a food revolution in America, with greater emphasis on organic food and animal rights. Just a week ago, Walmart called on suppliers to stop keeping calves in veal crates and hogs in gestation crates.
Something good could come from the California drought if it could push this revolution a bit further, by forcing a reallocation of water to the most efficient uses. But remember that the central challenge can’t be solved by a good rain because the larger problem is an irrational industrial food system.
Source: New York Times.
Water News for Early June, 2015
Water supply in up to 200,000 Ireland homes in danger of lead contamination. The water supply in up to 200,000 homes is in danger of lead contamination, in what has been described as a ‘public health risk’.Lead pipes were also found in schools and hospitals, with the problem believed to be particularly bad in Dublin.
Drought hastens decline of the Joshua tree, California’s desert symbol. It’s a tough time to be a Joshua tree. Climate change is taking an enormous toll, and the current drought has hastened the decline of a species that is regarded as the symbol of California deserts.
California moves to restrict water pumping by pre-1914 rights holders. For the first time in nearly 40 years, state regulators are telling more than 100 growers and irrigation districts with some of the oldest water rights in California that they have to stop drawing supplies from drought-starved rivers and streams in the Central Valley.
Clean water could take a central role in the 2016 presidential debates. Following the Obama administration’s introduction of the “clean water rule” last week, Republican presidential hopefuls have made water the latest issue in a campaign to denounce government overreach. An excellent analysis of the President’s “Clean Water Rule” from The Guardian.
In a drought, should we drink sewage? Singapore does. Surrounded by oceans but lacking adequate clean water resources, Singapore hopes to get 55% of its drinking water from recycled sewer water by 2060. The level might seem ludicrous if so many other countries weren’t confronting their own water shortages. Read the full article in USA Today.
Photo exhibit puts world’s water problems into perspective. A new exhibition of large-scale photographs at the Weinstein Gallery in Minneapolis aims to show the complicated relationships people around the world have with water and the environment. Minnesota Public Radio.
Some 50 million gallons of scarce California water were lost when an inflatable dam near San Francisco was vandalized. More.
Officials in Michigan are upset at Canada’s plan to bury nuclear wastes a mile from the shores of Lake Huron.
In the last Occasional we featured a piece describing how the Aral Sea was drained to satisfy the demand for water of Joseph Stalin’s cotton-growing venture. The wisdom of growing cotton in arid regions is being questioned. Cotton is one of the thirstiest crops in existence, and each acre cultivated here demands six times as much water as lettuce, 60 percent more than wheat. Excellent article from Pro Publica.
Indian government to review hydroelectric dams. Within a week, India’s ministry of environment and forest finds itself committed to conducting an overall impact assessment of dams in the rivers Ganga and Brahmaputra.
How can a river or lake be protected from pollution if the streams and creeks that feed into it are not?
A Baltimore Sun Editorial
Flowing water doesn’t respect state boundaries. It will keep moving from puddle to ditch to creek to stream to river without the slightest concern for whether it’s in the upper reaches of the Mississippi in Minnesota or far downstream in the Louisiana Delta. Pollution moves right along with it, so while states can exercise authority to regulate their own waters, the ultimate responsibility for protecting public health and clean water falls to the federal government.
Last week, President Barack Obama announced the new rules known as the “Waters of the United States” under which the U.S. Environmental Protection Agency and the U.S. Army Corps of Engineers will act to meet that very obligation under the 43-year-old Clean Water Act. The regulations seek to clarify legal uncertainties raised by two Supreme Court rulings over exactly how far upstream the federal government’s reach could extend.
Farmers and business groups have been quick to criticize the regulations — and have done so vehemently since they were first proposed a year ago — on the grounds that they are a costly bureaucratic overreach. Their Republican allies in Congress have echoed that chorus, hoping to paint Mr. Obama once again as an autocrat seeking to overstep the Constitutional limits of his office by regulating what he could not possibly achieve through the legislative process.
None of those complaints is true (aside from the fact that a politically gridlocked Congress is unlikely to pass any environmental legislation of consequence, good or bad, in the foreseeable future). What is clear is that Americans who want clean water running through their taps aren’t going to get it if major rivers are protected but the streams feeding into them are not.
A 30-foot-tall jackpump on the Hagerman refuge partially submerged by record flooding from Lake Texoma.
Lake Texoma — a reservoir built by German prisoners of war to prevent flooding on the Red River — breached its spillway last month for only the fourth time in its 71-year history. The lake finally crested May 31 at a record-high level of nearly 646 feet of water — more than 25 feet above its normal height. This one of many refuge areas that are ill equipped to handle the water pollution issues associated with flooding. Read “Floods expose weakness in FWS’s oil and gas oversight.”
Virginia waited two months to notify Kentucky of sewage leak into river. Kentucky officials are upset that it took two months for anyone in Virginia to tell them about the millions of gallons of sewage pouring into the Levisa Fork of the Big Sandy River and across the state line.
Nestle, faced with growing criticism for drawing water for its bottled water sales from wells in drought-stricken California, announced that it plans to introduce a “zero water” manufacturing system in some of its California food production locations. The plan is to extract water from milk used to manufacture dairy foods for use in regular plant operations. Nestle has such a “zero water” plant now in operation in Mexico. Press Release.
Complaints about golf courses in Vietnam increase. Critics say that golf courses in Vietnam use three to five times more chemicals than the same area of agriculture land. A golf course in Southeast Asia uses around 1.5 metric tons of chemicals per year on average and most of them end up in ground water and even pollute the air. Golf courses also use excessive amounts of water. An 18-hole course in Malaysia uses 5,000 cubic meters of water a day, which is enough for at least 20,000 households. Details from Than Mien News.
Crawling, breathing, invasive fish a ‘major disaster’ if it reaches Australia. The aggressive climbing perch, which can crawl on land, live for six days out of water and suffocate its predators, heads south from Papua New Guinea. Details, including a video of the crawling fish, from the Guardian.
The unimaginable water pollution that comes from animal manure.
Three hundred sixty-nine million tons—enough to fill the Dallas Cowboys stadium 133 times. That’s how much manure animals produced on factory farms in 2012, according to a new report by Food & Water Watch.
That’s 13 times more sewage than produced by the entire U.S. population during the same year.
It’s one big load of crap, for sure. But here’s the real kicker: Unlike sewage produced by cities, the manure on factory farms never undergoes wastewater treatment.
Where does all that untreated, antibiotic- and growth hormone-ridden waste end up? Festering in open lagoons, leaching into waterways, sprayed and spread onto open fields.
Statue of Haliburton founder Erle Haliburton in the company’s home town, Duncan, Oklahoma. It appears that the company’s main gift to current residents of Duncan is perchlorate in its water and soil. Read the excellent AlJazeera report.
New irrigation techniques have made it possible to increase yields with less water than farmers once thought they needed.
In Templeton, California, Mary Morwood Hart is using dry farming on her Grenache, Mourvedre, and olive trees, carefully cultivating the soil on her 20 acres so it can sustain growth without water. Over the past century, US agriculture has pushed itself to produce higher and higher yields by carefully engineering its plots: building larger farms with more advanced mechanics and increasing reliance on fertilizers, weedkillers, and pesticides. That’s brought more food to market. But it’s also depleted the soil—those steps tend to kill the microbes that build organic material and make it sponge-like.
Hart and other dry farmers think they can find a solution in the dirt itself. When soil is left to its own devices, it becomes rich in organic material. It loses less water to runoff and evaporation, and food can grow with little or no irrigation. Read: There’s a better way for California to water its farms.
The Complex Relationship Between Food and Water
Rice takes tons of water, because the fields are flooded. But that water doesn’t simply disappear — it seeps into the ground, and some of it goes back into the rivers. The water table in northern California is in good shape, in part because of all the rice paddies recharging the aquifers. Rice farmers flood their fields as a means of weed control, which allows them to dramatically reduce their pesticide use. And those fields provide important habitat for birds and fish — so important that the USDA’s Natural Resource Conservation Service is offering farmers money to continue flooding their fields to give migrating waterfowl a chance to survive the drought.
The point is that we can’t simply cure California’s drought by eating foods that require less water to produce. This Grist article takes a fresh look at the food/water relationship.
Artificial grass may save water, but does it endanger people? When Michael and Barbara Fouch first considered replacing their grassy lawn with artificial turf, they researched the growing array of options for the green plastic blades and the infill that holds them in place. The pros and cons of artificial lawns.
Forget April showers, this May was wettest in US records. Feeling soggy? Last month was the wettest on record for the contiguous United States, according to federal meteorologists.
B. Sharper, the Pure Water Gazette’s numerical wizard, puts out some facts about our oceans on World Oceans Day.
June 2015 date on which World Oceans Day was celebrated — 8.
Percentage of the Earth’s surface that is covered in water — 70+.
Percentage of this water that is in our oceans — 97%.
Pounds of plastics that we dump into our oceans each year — 19,000,000,000. (Nineteen billion.)
Number of feet that sea levels are expected to rise during this century –3.3.
Degrees Fahrenheit that sea surface temperatures rose over the past century — 0.18.
Percentage of the oceans’ fish stocks that are now considered to the overfished — 60%.
Jobs that were lost when one species of cod was overfished in 1992– 40,000.
At current rate of overfishing, according to some scientists, the date at which it is expected that we will simply run out of fish — 2055.
Percentage of marine predators that have already been removed from their habitats — 90%.
Percentage of Caribbean coral reefs that were damaged due to “coral bleaching” — 50%.
Percentage of the marine life that lives in coral reefs. — 25%.
Percentage of our carbon dioxide emissions that end up in the ocean — 30%.
Percentage of the oceans that have actually been explored by humans –less than 10%.
Pure Water Gazette technical writer Pure Water Annie explains
Common Protozoa that Infect Drinking Water and How to Get Rid of Them
by Gazette Technical Writer Pure Water Annie
The the most common protozoa that affect drinking water quality in the United States are Cryptospridium and Giardia. Both are intestinal parasites of warm-blooded animals. There are several species of each, and some can infect humans. Infection can come from recreational waters, drinking water, or food.
According to one authority, “Infection requires ingestion of about one to 10 organisms. Some infections are asymptomatic, so some people are not aware they are infected. Symptoms can include diarrhea and sometimes nausea, vomiting and fever. The infections are usually self-limiting, lasting several days for healthy people, but they can be chronic or fatal for less healthy or immunocompromised people.”
Both Cryptospridium and Giardia thrive in cold water, but Crypto cysts are sensitive to higher water temperature and can survive only about a week in 85 degree F. water. Both cysts are much more resistant to the usual water disinfectants than bacteria, and Cryptosporidium is virtually unaffected by regular municipal chlorination. Ozone and ultraviolet treatment are very effective for both, and because both cysts are relatively large, tight filtration devices like ultrafiltration, microfiltration, nanofiltration, and reverse osmosis easily remove them. In fact, a common treatment for both is conventional filtration in the two-micron range and tighter.
In a word, both cysts are fairly easily eliminated by point of use treatment like tight undersink filters and reverse osmosis and point of entry treatment by ultraviolet, but regular city water disinfection with chlorine and chloramine cannot be relied upon.
The size of the Giardia pictured above shows that the cysts are easily controlled by tight filtration devices like reverse osmosis and even conventional 1-micron filters.
More about Giardia.
More about Cryptosporidium.
How Much Water Should Humans Drink?
Gazette’s Introductory Note: Although asking how much water we should drink is in a way like asking how much air we should breath, since our intake of both of life’s essentials is mainly self-regulating, almost everyone who writes about health and nutrition has at some time chimed in on the topic of how much water a person should drink. Although we know of no one who believes in drinking zero water, quantity advice ranges from not much to gallons per day. The Gazette has consistently stuck with the radical “drink water when you’re thirsty” theory. Below is a view on the subject from a technical journal focused on water treatment. It is excerpted from a piece by Dr. Joseph Cotruvo.
The statement, “Water is life,” is not an exaggeration. All living plants and animals require regular and sufficient water consumption for survival, as well as for growth and development. Serious and even fatal outcomes can occur under extreme conditions of either seriously inadequate or very excessive water intake, and there might be some health benefits associated with consumption beyond the averages. Water is also a common element in Christian, Muslim and Jewish religious writings.
Daily water consumption occurs from several sources: Tap water, beverages and foods made with tap water, bottled water, bottled beverages and metabolic water that is produced from ingested food and its conversion to energy. The first four are obvious. The fifth, metabolic water, is created by living organisms through metabolism by digesting and oxidizing energy-containing substances in their food. Metabolism produces about 110 grams of water per 100 grams of fat, 41.3 grams of water per 100 grams of protein and 55 grams of water per 100 grams of starch. So, it adds a few hundred milliliters to our daily water intake.
How much water should we drink?
Ingested water serves many functions. It is essential for maintaining blood composition, salts balance and cellular osmotic pressure, and it aids digestion, helps eliminate wastes in urine and feces, provides a solvent/solute load for the kidneys and helps control body temperature through perspiration. It usually contains salts and some nutrients like calcium, magnesium, chloride, sulfate, sodium and potassium; and, uptake of essential minerals is often more efficient from water than from foods. Calcium and magnesium uptake from water and milk is in the range of 50 to 60 percent versus approximately 15 to 20 percent from foods.
It is important to consume water regularly, especially during physical stress conditions. I recall when coaches would not allow athletes to consume water during practice and games, ostensibly to prevent vomiting. Nowadays, we see them drinking constantly. Acute dehydration has immediate, measurable and adverse consequences. Fluid loss of one percent stimulates thirst and impairs thermoregulation. Vague discomfort and loss of appetite appears at two percent. Dry mouth appears at about three percent loss. At four percent loss, work capacity decreases by 20 to 30 percent. Headaches and sleepiness occur at about five percent loss. Collapse can occur at about seven percent, and a 10 percent loss is life-threatening.
Water intake is needed at a minimum to replace losses and prevent dehydration. Water is lost through urine, feces, respiration and evaporation. Young children, pregnant and lactating women, the elderly, heavy work and exercisers and persons with certain diseases have increased fluid requirements compared to the general sedentary population. Numerous studies have attempted to determine water needs, but in 1989 the National Research Council (NRC) concluded that because of the complexities, a Recommended Dietary Allowance (RDA) could not be established, but an Adequate Intake (AI) reference value was provided for healthy Canadian and American populations.
Water needs under conditions of physical stress, high temperature and humidity are substantial. Physically active individuals might sweat at the rate of three to four liters per hour under those conditions. Daily fluid requirements have been shown to range from as little as two liters per day to 16 liters per day. Several national military organizations have conducted studies of the water needs of troops under stressed survival and endurance requirements. A study of members of the Zimbabwe National Army doing strenuous work over 12 days showed that consumption of the test group was 11 liters per day versus seven liters per day in the control group.
The U.S. Army revised its water replacement guidelines to 0.5 liters per hour for an easy work rest cycle at 78o to 81.9o F to at least one liter per hour for a hard work/rest cycle of 10/50 minutes at > 90o F. The revision occurred after 190 military personnel were hospitalized over several years for hyponatremia (excess, unreplaced sodium loss by perspiration), which can be fatal when excessively large volumes of plain water were consumed in combination with a low sodium chloride diet.
Gender and age specific AIs were established by the NRC in 2004 (See Table 1).
|Zero to six months||0.7 assumed from human milk|
|Seven to 12 months||0.8 milk plus food and beverages|
|One to three years||1.3|
|Three to eight years||1.7|
|Nine to 13 years||2.4 boys, 2.1 girls|
|14 to 18 years||3.3 boys, 2.3 girls|
|19 to 70+||3.7 men, 2.7 women|
The values in Table 1 are applicable under typical, nonstressed conditions. For higher stress situations (e.g., athletes), the amount of water ingested should equal the amount lost, i.e., 1 kg of lost weight = 1 kg of water consumption. Alcohol has a known transient diuretic effect, but adequate fluid intake immediately following alcohol consumption will not result in appreciable fluid losses over a 24-hour period.
The World Health Organization’s (WHO) requirements in liters per day for adults are listed in Table 2.
|Sedentary, temperate env.||Physically active/increased temperature|
|Male adult||2.9||4.5 – 11.0|
How much water is actually consumed by U.S. citizens?
Regulatory agencies establish regulations for contaminants in water partly based upon assumed values for daily human tap water consumption. Precise determinations of actual consumption vary by individuals and conditions; so to simplify the regulatory decision, the U.S. Environmental Protection Agency (EPA) assumes lifetime consumption of two liters per day for a 70 kg adult, and one liter per day for a 10 kg child. WHO assumes two liters per day for a 60 kg adult and one liter per day for a 10 kg child. Canada assumes 1.5 liter per day for a 70 kg adult.
Several large-scale surveys have produced data on consumption of community water and/or total water by individuals and groups. Results tend to be in similar ranges given the margins of variability in these types of studies (e.g., Kahn; and Kahn and Stralka, 2008). For example, a 1989 report by Ershow and Cantor, using survey data for three consecutive days from 1977-78, concluded that the mean value for tap water consumption was 1.193 liters per person per day, and 88 percent consumed two liters per day or less. A more recent analysis of a survey for two, nonconsecutive days from 1994-96 (EPA, 2000) of 15,303 persons gave 0.927 liters per person per day as the average per capita ingestion of tap water. The estimated 90th percentile consumption was 2.016 liters per day (range 1.991 to 2.047). Some people reported drinking no tap water, so results for 14,012 “consumers only” were 1.0 liters per day (0.976 to 1.024) as the mean, and the 90th percentile value was 2.069 liters per day.
Values for “total water consumption” for “consumers only” were 1.241 liters per day (1.208 to 1.274) as the mean, and the estimated 90th and 95th percentiles were 2.345 and 2.922 liters per day, respectively. So, 83 percent of consumers only consumed two liters of water per day or less.
The average reported consumption for bottled water drinkers was 0.737 liters per day; the 90th and 95th percentile estimates were 1.568 liters per day and 1.971 liters per day.
The total water consumption average for all individuals was 1.232 liters per day, and the 90th and 95th percentiles were 2.341 and 2.908 liters per day. In this study, approximately 84 percent of the U.S. population consumed two liters or less per day. About 13 percent of the U.S. population water consumption in those studies was attributable to bottled water and 10 percent to other sources.
For children between one and 10 years old, the mean total water consumption was 0.528 liters per day, and the 90th and 95th values for total ingestion were 1.001 and 1.242 liters per day. Thus, 90 percent of children consume one liter of water per day or less.
Are there health benefits from greater water consumption?
Although it is difficult to precisely determine desirable and ideal water consumption levels, there are reports that people with greater water consumption may benefit more compared to those with less. Dehydration has been linked to increases in risks of urinary tract infections, dental disease, constipation, kidney stones and impaired cognitive function. Higher fluid intakes have been associated with reduced risks of urinary tract stones, colon and urinary tract cancer, and mitral valve prolapse in some studies. More research is necessary on this appealing hypothesis.
Conclusions: How do these approximate values compare to AIs and regulatory default assumptions?
It is clear that the actual water consumption in the U.S. is below the recommended AI values for almost every age group. Some additional water is provided by metabolism and nontap water sources, but the AI values would not likely be exceeded in many cases except perhaps for active high consumers.
Regarding the default water consumption values of two liters per day for adults and one liter per day for a 10 kg child, approximately 90 percent of adults are consuming two liters per day of tap water or less, and almost all very young children are consuming about one liter of tap water per day or less. So, water consumption levels indicate that drinking water standards are generally protective of the population and have greater margins of safety for essentially all very young children and virtually all adults. Additional conservatism is embedded in calculations of drinking water standards by inclusion of relative source contribution factors attributable to drinking water as a source. The usual default value is 20 percent which results in additional safety.
There are several studies indicating potential health benefits from long-term consumption of greater amounts of water, which is worth exploring further.
So, today’s take-home message is: More water and a little more salt is good for people with more strenuous activity. And, the good news is that community tap water in the U.S. is safe almost everywhere.
Article source: Water Technology.
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