System Non-potable Water

Non-potable water sources include rainwater, reclaimed/recycled water and gray water.  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 Building 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 projects 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 it is weighted even more heavily.  The use of non-potable water can contribute 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 longer 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 municipally supplied reclaimed or recycled water.  LEED points are awarded not only for the reduction in potable water use but also for diversion and reuse of storm and waste water that in conventional construction would leave the site.

A number of companies have pioneered systems for the collection, filtration and treatment of water for these non-potable applications.  Until recently the vast majority of this water was used outside of a structure for irrigation.  Only now are we beginning to truly appreciate the benefits of non-potable water applications.  As a result, there is increasing demand to convey non-potable water inside the building by installing a separate distribution system for this water to those fixtures and applications that can use it.  An engineer can now design a building and have thousands of gallons of non-potable water available for such uses.

From a codes and standards viewpoint non-potable water piping systems within a building is an area that is still under construction.  There are hearings and discussions currently underway, not only in the US but all around the world.  One thing everyone agrees on is that non-potable water systems must be clearly and easily identified for human health and safety reasons.  There must be no chance that a reasonable person would ever mistake a non-potable water supply line for a potable water line.