N on - potable water sources include rainwater, reclaimed/recycled water and greywater . While non - potable water is not appropriate for human consumption, it can be used in a myriad of other applications, such as doing laundry, toilet and urinal flushing, and cooling tower make - up water . Engineers and architects designing sustainable living and green building projects have a keen interest in utilizing non - potable water . One of the motivators for such projects is the U . S . Green Build - ing Council (USGBC) LEED green building certification program . There has been an increasing demand to design and build projects that, at a minimum, are LEED certified, and, in many cases, aim for LEED Silver or Gold . Under LEED 2 . 2 water conservation and innovative reuse were prime areas rich in LEED points . And under the new LEED 2009 (v3 . 0), it is weighted even more heavily . The use of non - potable water can con - tribute up to 10 LEED points on a project, an astounding 25% of the points needed to achieve a LEED certified building . In fact, the number of LEED points available for water efficiency is even higher if any of these credits are deemed a regional priority by the USGBC regional council or chapter . It is becoming clear that it is no lon - ger enough to simply install low - flow fixtures . Substantive steps must be taken to conserve the use of potable water by the innovative reuse of gray water, the collection and use of rainwater and, in more and more communities, the use of CODE - WISE, DEBATE CONTINUES ABOUT THIS PIPING . HOWEVER, THERE IS A CONSENSUS THAT THESE SYSTEMS MUST BE CLEARLY AND EASILY IDENTIFIED FOR HUMAN HEALTH AND SAFETY REASONS . BY VIC HINES, CPD, LEED - AP THE KEY BENEFIT OF NON - POTABLE WATER PIPING SYSTEMS Schematic of a rainwater harvest system courtesy of M/E Engineering, Rochester, NY . AS SEEN IN AR - PME (910)