In August, I climbed Mt. Kilimanjaro—the highest mountain in Africa, at 19,340 feet (5895 meters). I practiced by going for a three-day hike along the “Lost Coast” of California. One thing I noticed while hiking is that you're continually thinking about water. How much do you need to carry on your back? Do you have enough water to last until you can refill your supply? How do you take water from a stream and make it safe to drink?

When I left for Tanzania, I ran a campaign to raise money for charity:water, a non-profit that brings clean and safe drinking water to people in developing nations. Many of us take water for granted: you turn on the tap, or buy a bottle at the store, and there it is. But it's not like that for everyone. Many people in the world have to think about water all the time. People often walk miles to get water and miles to carry it back, and worry about whether it’s safe to drink. More than a billion people lack access to clean drinking water. As a result of unsafe water and bad sanitation, people in some developing countries are more likely to contract illnesses that are basically preventable but still kill thousands of people, including many children, every day.

Organizations are stepping up to the plate to focus on this issue. While there is much more work to do, the United Nations is on track to meet its Millennium Development Goal of halving, by 2015, the proportion of the population without sustainable access to safe drinking water and basic sanitation. This year’s Blog Action Day theme is water, and with that in mind, we thought we’d share a bit about Google’s efforts to conserve water, in a variety of ways.

One of key area where we can make a contribution is through our data center operations. On average, two gallons of water is consumed for every kilowatt-hour of electricity produced in the U.S., because water is needed for power plants to operate. That means that by building what we believe to be the most efficient data centers in the industry, we’re saving fresh water. Every year, our data centers save hundreds of millions of gallons of drinking water simply by consuming 50% less electricity than the industry average for technology companies.

A major reason why our data centers are so energy efficient is that we use evaporation to cool our facilities, rather than a more traditional chiller. Evaporative cooling uses far less power than a chiller—so by using a fraction of a gallon of water for evaporative cooling, we save a gallon of water at the power plant. We’ve also made an effort to minimize the amount of fresh water directly consumed by our facilities by using recycled water. Rather than use clean, potable water, we treat wastewater until it’s clean enough to be used for cooling. Two of our data centers run on 100% recycled water already—one by filtering water taken from an industrial canal, and one by taking “greywater” from a city wastewater treatment plant and cleaning it before using it in our cooling towers. We’re also working on new, geographically appropriate systems, like large rainwater capture ponds at one site and a seawater cooling system at a data center that is currently under construction. We set an aggressive goal a few years ago to use recycled water for 80% of our total data center water consumption by the end of 2010. Although we’re unlikely to meet that stretch goal, we believe we’ve made a lot of progress and are hopeful that by the end of this year recycled water will account for almost half of our total consumption.

We’ve also made some small changes at the Googleplex in Mountain View. Earlier this spring, we worked with the city of Mountain View to become the first commercial customer of recycled water for irrigation. We’re using it now on our sports fields as well as in a few of our buildings here in Mountain View. A few years ago we did water audits of our buildings to determine where we could make changes to save more water. We’ve since refreshed several of our buildings with new, very low-water use fixtures. And we’ve also experimented with phasing out the use of bottled water on campus, replacing plastic bottles with water filters and reusable cups. Not only does bottled water use up more energy in production and transportation, and create waste through plastic bottles (many of which are never recycled)—the Sierra Club estimates (PDF) that it takes three liters of water to produce one liter of bottled water.

This Blog Action Day, I hope you’ll take a moment to reflect on your own water use, and on what you might be able to do to make a difference. You don’t have to climb a mountain to help others gain access to clean water.