SAN FRANCISCO, CALIF. -- Water. it's one of our most precious resources. and it's one that many people take for granted.

At the farmer's market at San Francisco's Civic Center Plaza, people flock to the stands looking for the perfect melon or juiciest strawberry.  But most people don't think about how much water it takes to produce their produce.

The website, waterfootprint.org, thought a lot about it and did the calculations. For example, it takes about 121 gallons of water to make a single orange. a tomato takes 47 gallons, but a peach or a nectarine...317 gallons!

Heather Cooley, from the Pacific Institute said, "I do think that footprinting can educate people about how we do use water in everything we do. It really is an important resource and it comes from somewhere other than my tap."  Cooley studies water as a senior researcher at the Pacific Institute. and while she believes turning off your faucet, when brushing your teeth or doing the dishes, is a good thing, household water use accounts for only 6 percent of the water that we consume. Cooley continued, "I think most people are not aware of that so, water footprinting really gives them a way to think about those connections and to think about how they use water."

But thinking about water usage is hard for some people to swallow.

Cooley wants to get to the root of the issue: farms. She said that by reducing water use in our farms, in our businesses, it can reduce the water footprint in general for an individual, a business, and even a country or the globe. But that takes money. something that's a lot more scarce than water right now.