On a recent blog post, Jim Brown, Google’s data center facilities manager, wrote that the company is taking a multi-pronged approach to going green. He writes, “Google’s data centers use half the energy of a typical data center in part because we rely on free cooling rather than energy hungry mechanical chillers.”

At many of Google’s data centers, the company uses evaporative cooling, which uses cold water for cooling, and releases the resultant water vapor through cooling towers. The Georgia data center goes one step further by using 100% gray, or recycled water, for its cooling needs. The local water authority cleans wastewater from the local communities and releases it back into the nearby Chattahoochee River. Google worked with the local authority—Douglasville-Douglas County Water and Sewer Authority (WSA)—to build a side-stream plant about five miles west of the data center that diverts up to 30 percent of the water that would have gone back into the river. Instead, the water is sent it through the side-stream plant for treatment and then on to the data center.

“Any water that doesn’t evaporate during the cooling process then goes to an effluent treatment plant located on-site. There, we treat the water once again to disinfect it, remove mineral solids, and send it back out to the Chattahoochee—clean, clear, and safe,” Brown writes.

The Chattahoochee was the first river to be designated a National Water Trail in a new system announced by the Secretary of the Interior Ken Salazar—a system that encourages community stewardship of local waterways.

“We’re glad to do our part in creating an environmentally sustainable economy along the shores of the Hooch,” Brown added.