Forget oil and natural gas. The truly worthwhile commodity in which to invest in the 21st century is water, say a growing number of economists and market gurus.

That is, if you subscribe to the notion that water should be a commodity.

The chorus of analysts and trend spotters calling for investors to pile into water as an investment class is giving new life to a long-simmering debate: Whether water is a commodity, to be bought and sold like all others, or a human right that can be denied to no one.

And for Canada -- one of the world's largest sources of renewable freshwater -- that debate is becoming personal.

The latest salvo in the debate came Thursday when Citibank chief economist Willem Buiter declared his belief that the water market will become larger than the oil market this century.
"I expect to see in the near future a massive expansion of investment in the water sector, including the production of fresh, clean water from other sources (desalination, purification), storage, shipping and transportation of water," Butler said in a memo quoted at the Alphaville blog. "I expect to see pipeline networks that will exceed the capacity of those for oil and gas today."

Buiter argues that water is an asset class with the capacity to eclipse "oil, copper, agricultural commodities and precious metals."

Buiter's words echo those of Richard Sandor, described by the Wall Street Journal as the "principal architect" of the carbon-trading market, who said earlier this week that water "is going to be the commodity of the 21st century."

But the hopes of investors who see the "next big thing" in the water trade are clashing head-on with a growing movement to have water declared a human right.

For Canada, that debate will likely be particularly vexing. With seven per cent of the world's renewable freshwater supply but less than 0.5 per cent of its population, Canada stands to become one of the world's largest water exporters.

But Canada's politicians have long been aware of the electorate's fear that the country's lakes and rivers could dry up amid mass water exports to the United States, and have distanced themselves from proposals to do so.

Yet Canada's actions on the world stage in recent years have suggested that the country's leadership may be quietly following a different track. In 2010, Canada was one of a handful of countries to abstain from a UN vote declaring water to be a universal human right. That follows a 2002 vote in which Canada was the only country to oppose the notion of water as a human right.

Leaders who back Canada's position say declaring water a human right would mean the country would not be able to refuse to sell water to the US. But critics say that argument has it backwards, and that commodifying water would force Canada to sell by the gallon.

"The notion that water should be bought and sold like any other product is what threatens Canada’s control over its water – not the recognition of water as a human right," the Council of Canadians declared. "Trade agreements such as the North American Free Trade Agreement (NAFTA) and the General Agreement on Trade in Services (GATS) ensure that once water is treated as a commodity, Canada will have little power to stop or even to slow down the export of the resource."

But Canada's image as a major source of freshwater is somewhat deceptive. Some 60 per cent of the freshwater supply in this country flows to the Arctic Ocean, far away from the major population centres. And, as Environment Canada notes, Canadians are already the world's largest per-capita consumers of water. That would leave Canadian consumers vulnerable in a world of commodified water.

Earlier this month, Liberal Party water critic Frances Scarpaleggia called on the federal government to develop a comprehensive water strategy.

"While a national water strategy must include numerous components, one of the first priorities must be to settle, once and for all, the debate over bulk-water exports," Scarpaleggia wrote. "Although Canada is perceived ... as a water-rich country, the fact remains that our fresh water is a precious resource that we must not take for granted as an inexhaustible well of plenty."