Poet Henry Wadsworth Longfellow once said, "Into each life, some rain must fall."For the United States Army Reserve, the mission is life, and rain is an opportunity to be an agile, innovative force in the Department of Defense.The Army Reserve Water Security Implementation Strategy guides the Command's efforts to conserve mission-critical water assets. Goal Three of the strategy is "Utilize Alternative Water Sources," or sustainable sources of water that reduce the demand for fresh surface water and groundwater.One alternative water source is rainwater.Rainwater harvesting can save the Army Reserve's natural resources and bolster its water security for the future. To that end, the Army Reserve Installation Management Directorate and Pacific Northwest National Laboratory (PNNL) have implemented rainwater harvesting at vehicle wash facilities in the 63rd and 81st Regional Support Commands.Susan Loper, an analyst with PNNL, said that rainwater harvesting for vehicle wash is a particularly viable initiative for the Army Reserve. "Vehicle wash is more common at Army Reserve sites, compared to other non-potable water applications such as irrigation," she explained.Over 460 Army Reserve Centers across the country have vehicle maintenance facilities.To identify potential sites for rainwater harvesting, a team from the Army Reserve Installation Management Directorate and PNNL conducted a strategic geospatial study. The study examined factors such as rainfall, water use, water demand and watershed vulnerability, which indicates an area where the potable water supply is or will be threatened. About 42 percent of Army Reserve facilities are in "vulnerable" areas.With the results of the study, the team identified over 300 facilities in the Southeast, Northeast and Midwest regions of the continental United States as suitable candidates for rainwater harvesting. Ultimately, they selected Grand Prairie Army Reserve Center in Grand Prairie, Texas and Harry Milton Kandel Army Reserve Center in Savannah, Georgia as pilot sites.According to Loper, Grand Prairie Army Reserve Center and Harry Milton Kandel Army Reserve Center have relatively high demands for vehicle wash. Rainwater harvesting can fulfill most, if not all, of those demands. Equally significant, Grand Prairie and Savannah are in vulnerable watersheds due to numerous environmental, economic and social factors.Rainwater harvesting will conserve valuable potable water resources for the Army Reserve. Potentially, the Grand Prairie site will supply 140,000 gallons of rainwater each year, and the Savannah site will supply 200,000 gallons of rainwater each year.The projects will also support the Command's efforts to reach federal water use reduction goals. As a federal entity, the Army Reserve must reduce its water use intensity by two percent annually -- for a total reduction of 36 percent -- by 2025, compared to a 2007 baseline. The Army Reserve has reduced water use intensity across the enterprise by 44 percent since 2007, far exceeding the goal.Furthermore, rainwater harvesting will leverage partnerships between the Army Reserve and its stakeholders. Contractors installed the pilot systems at the sites in February and March 2017. On-site professionals will operate and maintain the systems. The Army Reserve Installation Management Directorate and PNNL will monitor the systems during their first years of operation.Finally, and importantly, rainwater harvesting will enhance the Army Reserve's mission readiness because it saves potable water for the enterprise's most valuable resource -- its Soldiers."Water is absolutely necessary for us to train," said Trey Lewis, Army Reserve Water Program Coordinator. As a former Soldier, Lewis personally understands water's vital role in the military's battle rhythm. "We can train without internet access. We can train without electricity. For a limited time, we can even train without food. If we run out of water, we're done, and we're done right away. In a cantonment area, the toilets do not flush. The sinks do not flow. Everything shuts down. In a field environment, a water shortage can become a life or death situation, especially in hot summers when training is at its most intense. Rainwater harvesting helps us avert situations that would delay or stop training, get in front of the curve during natural disasters, and help us become -- in the event of an emergency -- an asset that can provide assistance and security instead of a liability that needs assistance."Lewis visited the Savannah site, and his impressions were favorable. He said that, so far, the personnel at the Army Reserve Center's vehicle wash facility are pleased with the rainwater harvesting system's performance. "Overall, [the project] seems promising," he remarked.The Army Reserve depends on water to sustain its warfighters, maintain its facilities and accomplish its missions. As the Command strives to protect its resources, the Army Reserve Installation Management Directorate and PNNL are driving advanced solutions to water security. Cutting-edge technologies such as rainwater harvesting will protect precious natural assets, support Soldiers and fully enable the defense the nation -- now and in the future.Learn more about Army Reserve water conservation initiatives at sustainableusar.com. Find us on Facebook at facebook.com/SustainableUSAR and follow us on Twitter @SustainableUSAR.