A surprising amount of water is hidden in a chocolate bar. Photo: Sandra Postel

As Valentine’s Day approaches, no doubt many of us have chocolate on our minds and taste buds.

Delicious, dark, tempting chocolate that, eaten in moderation, may even be good for us. As we’ve learned in recent years, the cocoa beans that give chocolate its main ingredient contain flavanols, which scientists have discovered may reduce the risk of heart disease.

More love for chocolate.

But there’s a hidden ingredient of chocolate we might also give more love to – and that’s water.

It takes an astonishing 450 gallons (1700 liters) of water to make a typical 3.5-ounce (100-gram) chocolate bar. That’s about ten bathtubs of water for one bar of chocolate.

Most of those gallons are consumed by the cocoa plants in the field. As with other products of the land – from coffee to cotton shirts – it’s the water needed for plant growth that typically accounts for the biggest portion of that item’s water footprint.

In the case of chocolate, where does that water come from?

The most ideal climate and growing conditions for cocoa (or cacao) plants occur within a 10-degree latitude band around the equator. The West African nation of Côte d’Ivoire (Ivory Coast) is the world’s largest cocoa producer, and its neighbors Ghana, Nigeria and Cameroon rank high as well.

In fact, more than half of the water consumed to produce chocolates eaten in the United States comes from rain falling in West Africa. (Click here to learn more about where the U.S. water footprint for chocolate and other products lands around the world.)

So as we share the love this Valentine’s Day, let’s send a little bit to the rain that grows the beans that make the chocolates we’ll be savoring.

Sandra Postel is director of the Global Water Policy Project, Freshwater Fellow of the National Geographic Society, and author of several books and numerous articles on global water issues. She is co-creator of Change the Course, the national freshwater conservation and restoration campaign being piloted in the Colorado River Basin.