How Water Footprinting is More Complex than Carbon

What's the best way to save water?

Hint: It's not by taking a quick shower. Or using a dual-flush toilet. Or planting native grasses rather than a thirsty lawn.

Those are all good practices, but you'll make more of a difference if you skip your next cheeseburger. Or -- surprisingly -- order a Coke instead of a glass of orange juice.

This, at least, is one conclusion to be drawn from a report issued today by The Coca-Cola Co. and the Nature Conservancy, with the decidedly unsexy name of Product Water Footprint Assessments: Practical Application in Corporate Water Stewardship [PDF, download]. The name may be uninspired but the 48-page report makes for interesting reading and not only if your business, like Coca-Cola's, depends on access to clean water.

"We don't have a business without water," says Denise Knight, who is the water and sustainable agriculture director for Coca-Cola. As the world's largest beverage company (2009 revenues: $31 billion), Coca-Cola has focused on water as an environmental issue for nearly a decade. Knight, who joined in 2005 to spearhead the company's water and ag work, spoke to me by phone from Stockholm, where it's World Water Week, an occasion for thousands to gather to discuss global water issues.

Coca-Cola has recognized for years that water is a risk factor in its business; the company got a wake-up call after it was accused of hogging too much water in India. About five years ago, it set a number of aggressive water conservation goals, mostly focused on the efficient use and treatment of water when making its products.

It made sense for the company and its bottlers to begin by focusing on their own operations, which they can control. But a big reason why Coca Cola now sees value in measuring the water footprint of its products (as opposed to the efficiency of its bottling plants) is that product footprints place water in a wider context, one that encompasses not just the direct use of water in a factory but its indirect use in the company's supply chain -- in the fields, if you will.

Agriculture, in other words, matters a lot when it comes to using water wisely. One data point: It takes 1,000 times more water to grow food for an individual than to meet that person's needs for drinking, according to the report.

So what's a water footprint? The report says:

A product water footprint is the total volume of freshwater consumed, directly and indirectly, to produce a product.

That may sound simple, but it's not. The Nature Conservancy and Coca-Cola report uses methodology developed by academics and others who are part of the Water Footprint Network, a Dutch nonprofit. It makes distinctions among three kinds of water -- green water which is the rainwater stored in soil and used for growing crops, blue water which is the water from rivers, lakes and acquifers used for growing crops or in manufacturing or in the products themselves, and grey water which is the volume of freshwater needed to assimilate pollutants created in agriculture and manufacturing. (And you thought carbon footprints were complicated!) Further complexity arises from the fact that water, unlike carbon, is a local resource, and usage should therefore be considered in the context of the local watershed.

Now that you understand the definitions, here are some findings in the report:

An 0.5 liter Coca-Cola in a PET bottle produced in the Netherlands has a green water footprint of 15 liters, a blue water footprint of 1 liter and a grey water footprint of 12 liters.

The company looked at Coke made in the Netherlands in order to work with a professor at the University of Twente who pioneered the idea of water footprints. Most of Coke's footprint comes from the sugar so the company then studied that ingredient and found that:

A kilogram of sugar beets sourced in Europe has, on average, a green water footprint of 375 liters, a blue water footprint of 54 liters and a grey water footprint of 128 liters.

It also look at orange juice sold in the U.S. by its Minute Maid unit:

Minute Maid Original orange juice (reconstituted from concentrate) in a 64 oz. fiber-based board gable-top carton, assuming the oranges are sourced in Florida or Costa Rica, has a green water footprint of 407 liters per liter of product, a blue water footprint of 127 liters, and a grey water footprint of 84 liters.