03/29/2012 02:49 pm ET Updated May 29, 2012

In Honor of World Water Day, Meet a Guy Who Uses Enough Water for a City of 40,000 People

Laurie Arthur is a farmer in the heart of Australia's bread basket, the basin of the Murray River, who was kind enough, when I was trying to understand water, to explain how water works for farmers.

Arthur lives out in the wide open country east of Adelaide and north of Melbourne -- flat, irrigated farmland where his nearest neighbor is 12 miles down the road, and where his white farm truck is often flanked by squads of kangaroos, who have no trouble keeping pace as he drives from field to field at 40 or 50 mph.

Arthur lives comfortably in a world most of us never visit, and even have a hard time grasping. He farms 10,000 acres. That amount of land is impossible to visualize, but its scale is easy to bring down to Earth.

He took me to a single 150-acre field, which seemed to spread out in all directions toward the horizon. (You could park five Wal-Mart Supercenters, including their full parking lots, on that one patch of dirt.) That single field has a perimeter of 2 miles.

It is 1 percent of Laurie Arthur's land.

If the land Arthur is responsible for cultivating is hard to grasp, the water he uses to make it blossom it is truly astonishing.

To raise a single year's crop, Arthur uses 1.6 billion gallons of water (6 billion liters) -- a big slug of water. It's enough to supply all the water needs for a town of 40,000 people, for a year.

One guy, with one farm, using as much water every single day as a city of 40,000 people.

Laurie Arthur has the charm and wry humor we find so irresistible in Australians -- the disarming confidence that comes from being self-reliant, the bemused understanding that in the developed world, farmers are far more alien creatures than, oh, astronauts.

He has introduced himself at school parent events as a farmer, and had fellow parents turn to him matter-of-factly and say, "Oh, you're a water waster, then."

What is Laurie Arthur doing with all that water, anyway?

He's raising food. Rice, to be specific.

In a year when everything goes right, Arthur raises 20 million pounds of rice, using those 1.6 billion gallons of water.

Is that good, or is that cavalier?

Well, with enough water to supply a city of 40,000 people for a year, he raises enough food to feed a city of 100,000 people for a year -- all 100,000 people, 3 meals a day, for 365 days.*

Arthur smiles. "How much is the right amount of water to feed a city of 100,000 people?"

Today is World Water Day. The point of World Water Day is to draw attention to our favorite, our most familiar, and our most taken-for-granted resource. There is a delightful irony for water folks in the fact that World Water Day is itself mostly ignored by everyone outside the world of water. (Could we start a day to draw awareness to World Water Day?)

Every person on Earth revels in water every day, in some fashion -- whether we celebrate water or not.

This year, the theme of World Water Day is the connection between water and food. Although most of us never think about water when we tuck into an omelet, or a turkey sandwich, or a dinner of salad, steak and rice pilaf, there is no more intimate connection than that between water and food.

The connection is so close, that for water folks there is a handy rule of thumb: In the developed world, 1 calorie of food requires 1 liter of water to produce.

A large tomato has 33 calories -- it required 33 liters of water to grow (almost 9 gallons).

A 12-ounce can of Coke or Pepsi has 140 calories -- so it required 140 liters of water to produce; 12 ounces of soda requires 37 gallons of water -- if you reach back and include the water necessary to raise the sugar in the soda.

A medium-sized McDonald's Big Mac Value Meal -- Big Mac, medium soda, medium fries -- has 1,130 calories, so the food required 1,130 liters of water, about 300 gallons.

The standard daily U.S. diet of 1,800 calories requires about 475 gallons of water to produce -- every day, for every American.

The 1-calorie-1-liter benchmark is a rough average. It takes far less water, for instance, to grow a pound of tomatoes than to grow a pound of beef.

What's handy about the rule is that it is a great way of waking up to how much water our food requires.

The average American uses 99 gallons of water at home each day -- real water, for showering and dishwashing, for toilet-flushing and making lemonade.

The average American uses another 250 gallons of water a day at home for electricity -- the electricity that each American uses, just at home, requires 250 gallons a day to generate. That's real water too, of course, we just never see it.

And the average American uses another 475 gallons of water day for food.

The food you eat each day requires five times the amount of water to create as the amount of actual water you use each day.

And that's true for the whole world. Food -- farming -- is the most important part of the world of water.

Worldwide, farmers use 70 percent of the water used each day.

And farming is not very efficient. The general rule of thumb is that farmers waste half the water they put on their fields. In the world of water, that "wasted" water has a very precise meaning. It means that half the water farmers use doesn't increase their production at all -- they could, with better management, use half the water they do and produce the same amount of food. Or they could use the water they are using and grow twice the amount of food.

But that inefficient use of water is actually good news.

In the next 35 years, we're going to add 2 billion people to the world. For every hundred people already here, we're going to add 29 more. They are going to be thirsty, and they are also going to be hungry -- which, as we've seen, is a form of thirst.

Current farming methods in many places are so water-inefficient that there's plenty of room to produce more food without having to use more water.

In fact, one of the most dramatic stories comes from the farms of the United States.

Water for irrigating U.S. farms peaked in 1980 -- more than 30 years ago, when there were 80 million fewer people than today.

U.S. farmers use 15 percent less total water today than in 1980, and they produce 70 percent more food. U.S. farmers have increased their "water productivity" by 100 percent in 30 years.

That's exactly the kind of progress we need to make to have both enough food for 2 billion more people, and enough water.

So what about Laurie Arthur, the Australian farmer who uses enough water for a city of 40,000 people to produce enough food for 100,000 people?

By almost any standard measure, Laurie Arthur is doing very well.

In the U.S., remember, our food requires five times the amount of water as the actual water we drink.

In the "city" Laurie Arthur is supplying, the ratio is the opposite: The food for each person he's feeding would require half the amount of "real" water that person would use in a typical day.

Using the 1-calorie-1-liter rule, Arthur is doing even better. Every liter of water he uses produces not one calorie of food, but six calories.

Still, even on a well-run farm, with a man who thinks about water all the time, the water required is mind-boggling.

A single, appealing mound of Japonica rice on your dinner plate tonight requires 14 gallons of water to produce. Imagine that fluffy pile surrounded by 14 gallon jugs of water. It seems truly astonishing. But it's a window on how removed we've become from the work required to get us our food -- and the water, too.

Every day is world water day, we just don't realize it.


* If you doubt the math that 20 million pounds of rice is enough to feed 100,000 people for a year -- the short version works like this. That comes to 4 pounds of rice per person, per week -- and one pound of dry rice provides about 3,200 calories. So four pounds is 12,800 calories, or 1,800 calories a day. Not that you'd want to eat rice three meals a day, for a year -- or that you could survive nutritionally on it. But Arthur's point is that he raises enough calories to feed a city for a year, and he's right.