“Over the coming decades, feeding a growing global population and ensuring food and nutrition security for all will depend on increasing food production. This, in turn, means ensuring the sustainable use of our most critical finite source ­ water.” – Ban Ki-moon, former UN Secretary General


“With ever more water needed to raise crops to feed the burgeoning global population, efforts to produce more food with less water are critical to averting a crisis,” warned experts from the InternationalWater Management Institute (IWMI).

With this statement, the world has to think not just once but twice.  Contrary to what most people believe, it’s not dwindling land areas that poses the biggest threat to food security; it’s actually watershortage.

“Many well-informed individuals see a future of water shortages, but few have connected the dots to see that a future of water shortages will also be a future of food shortages,” said Lester R. Brown, thepresident of the Washington, D.C.-based Earth Policy Institute.

“Water shortages lag only climate change and population growth as a threat to the human future,” said Brown in an exclusive interview by this author.  “The challenge is not to get enough water to drink, but to get enough water to produce our food.  We drink, in one form or another, perhaps 4 liters of water per day.  But the food we consume each day requires 2,000 liters of water to produce, or 500 times as much.”

A closer look at the available statistics proves him right.  Agriculture is by far the biggest consumer of water around the world.  In thickly-populated Asia, agriculture accounts for 86% of the total annualwater withdrawal, compared with 49% in North and Central America and 38% in Europe. 

“Agriculture is where future water shortages will be most acute,” wrote Michael S. Serrill in the newsweekly Time some years back. 

Rice, the country’s staple food, is a case in point.  “Water has contributed most to the grown in rice production for the past 30 years,” said the Laguna-based International Rice Research Institute (IRRI).  Irrigation-farmed rice draws heavily on the resource.

In his book, Water: The International Crisis, Robin Clark reports that an average farmer needs 5,000 liters of water to produce one kilogram of rice.  “Rice growing is a heavy consumer of water,” agrees theIRRI report, “Water: A Looming Crisis.”

The IRRI report projected that most Asian countries will have severe water problems by 2025.  This water shortage could seriously threaten rice production in the region. 

This is bad news for Filipinos who consider rice as their “deepest comfort food.” Each day, about 31,450 metric tons of rice are being consumed by Filipinos, according to Secretary Emmanuel F. Piñol of theDepartment of Agriculture.

“The link between water and food is strong,” Brown reminded. 

This is particularly true when it comes to crop production.  “It is largely because of the physiologic process of plant transpiration,” explained David Molden, Charlotte de Fraiture, and Frank Rijsberman in their paper, “Water Scarcity: The Food Factor.” “Huge amounts of water are evaporated constantly from pores on the surface of a plant’s leaves.  This evaporation is part of the process of photosynthesis, in which a plant manufactures its own energy from sunlight.

“Evaporation also helps cool the plant and carries nutrients to all its parts,” the authors continued.  “In addition to transpiration, some liquid water is turned to vapor through evaporation from wet soils or leaves.”

Molden is IWMI’s deputy director general while de Fraiture is a principal researcher at the institute.  Rijsberman was its ex-director general.  In their paper, they explained that crop yield is directly proportional to transpiration: more yield requires more transpiration.

“It takes between 500 to 400 liters of evapotranspiration (ET, the combined process of evaporation and transpiration) to produce just one kilogram of grain,” they wrote.  “When that grain is fed to animals, producing a kilogram of meat takes much more water – between 5,000 and 15,000 liters.”

Water is needed when planting crops.  Global food: Waste not, Want not, published by the Institute of Mechanical Engineers (IME), showed that a farmer who plants cabbage has to water his crop with 237 liters to come up with 1 kilogram of the leafy vegetable.  To produce a kilogram of tomato, about 214 liters of water is needed.

A kilogram of apple, the IME publication said, needs 822 liters of water while one kilogram of banana needs lesser: 790 liters of water.  Potato has even lesser: 287 liters of water for every kilogram.

Around the world, more than 40% of wheat, rye, oats and corn production is fed to animals, along with 250 million tons of soybeans and other oilseeds.  “Feeding grain to livestock improves their fertility and growth, but it sets up a de facto competition for food between man and people,” the institute says.

Without water, crops cannot grow.  “The total water requirement for the crop is the sum of the daily requirements for every day of the season,” explain Jacob Mittleider and Andrew Nelson, authors of Food for Everyone.  “It drops as low as 6 to 8 inches for short-season crops in humid climates.  It may be 30 to 40 inches for long-season crops in arid climates.”

Total requirements for water vary with plant species and climate, the book stated.  “Some plants require more water at certain times of their growth than others,” it said.  “For example, annual crops while still young and small require only a small amount of water.  However, because their roots are limited to a small volume of soil, they might need frequent but light supplements of water.  Older and larger plants usually have more extensive root system, and even they may require more water, they may perform better since their roots can reach to a larger reservoir of moisture.”

Water, not land, is indeed the world’s most important resource.  “We’re surrounded by a hidden world of water,” pointed out Stephen Leahy, a Canadian journalist and author. “Liters and liters of it are consumed by everything we eat, and everything we use and buy.”

That’s what he calls as “water footprint.”  In his book, aptly entitled Your Water Footprint, he defines it as the amount of water ‘consumed’ to make, grow or produce something.  “I use the word consumed to make it clear this is water that can no longer be used for anything else,” he explained.

According to him, one of the biggest surprises (while writing the book) was learning how small direct use of water for drinking, cooking and showering is by comparison.  For instance, he found out that flushing toilets is the biggest water daily use – not showers. While low-flow shower heads and toilets are great water savers, the water footprint concept can lead to even bigger reductions in water consumption.

“For example, green fuels may not be so green from a water consumption perspective,” Leahy wrote.  “Biodiesel made from soybeans has an enormous water footprint, averaging more than 11,000 liters per liter of biodiesel. And this doesn’t include the large amounts of water needed for processing. Why so much water? Green plants aren’t ‘energy-dense,’ so it takes a lot of soy to make the fuel.”

Water is a finite resource and it is dwindling.  “World demand for water doubles every 21 years, but the volume available is the same as it was in the Roman times,” observes Sir Crispin Tickell, former British ambassador to the United Nations and one of the organizers of the 1992 Earth Summit in Rio de Janeiro.  “Something has got to give.”

Again, here’s thought-provoking statement from Brown: “The most important thing we can do to cope with water scarcity is to use water more efficiently in agriculture.  Beyond this, urban recycling ofwater, still in its early stages, will be one of the keys in dealing with fast-spreading water shortages.” (To be continued)