Water efficiency seems secondary to the always demanding energy efficiency, but through consideration and proper design, significant savings await.  The collection of various site water sources, purposed for various needs, will result in an economic return.  Analogous to other systems, efficiency advances require capital investments to collect, treat and distribute.  The associated operating and maintenance routines increase in importance.  The rise in utilities should motivate all building owners to, at the very least, consider the concepts.  Implementation is more demanding than a traditional design, therefore owners should decide what water to harvest and reuse in the early design stages.  Owners need to be aware of the major components and the interdisciplinary impact.  Any water system beyond the norm might require storage, filters, pumps, treatment, additional piping, and space.  The common inputs are rainwater, process water, grey water, cold condensate, ...