by Dan Shalloway
Special to GreenGroup.com
LEED Accredited Professional

Last week we discussed site issues which are part of building Green. This week we investigate Water Efficiency.

In the United States approximately 340 billion gallons of fresh water are withdrawn per day from rivers streams and reservoirs to support residential, commercial, industrial, agricultural and recreational users. In addition, water is withdrawn from underground aquifers at a rate that has threatened many historic groundwater sources. Americans extract 3,700 billion gallons more per year than they return to the natural water system. The LEED rating system used by the US Green Building Council recognizes the importance of conserving water and devotes an entire section to performance standards for improving water efficiency.

One of the easiest ways to reduce water usage is by utilizing water efficient landscaping. By utilizing native plants which are acclimated to the local weather patterns the use of irrigation can be reduced or eliminated. Where irrigation is still needed, rainwater can be captured in underground cisterns and reused instead of irrigating from new sources. More efficient irrigation systems can be used such as drip irrigation and microjets which reduce the amount of water lost to evaporation.

Waste water is typically divided into Graywater and Blackwater. Graywater is house-hold wastewater which has not come into contact with toilet water. It typically does not include waste-water from kitchen sinks and dishwashers. Graywater can be used for irrigation with little to no treatment.

By use of innovative Wastewater technologies, Blackwater volumes can also be reduced. High efficiency toilets and urinals should be specified and dry fixtures such as composting toilets and dry urinals are available. For larger water users there are even options for on-site treatment of wastewater so that there can be 100% reuse.

So how does this all fit together? A modern office or apartment building can be designed so that rainwater from the roof scuppers is directed to an underground cistern along with all of the buildings Graywater. This stored Graywater and rainwater is then used for irrigation plus other non-potable uses such as flushing toilets and urinals. Only the final Blackwater from those toilets and urinals is disposed of.

Let me take a moment to reiterate the importance of making sure that a building or project that claims to be Green actually has the proper credentials. I was at a festival this weekend and there was a project that was advertising itself as a “Green” development. It’s brochure talked about the beautiful preserves and daily Yoga classes but the project had no certification by the US Green Building Council or any other recognized Green Group. In the end it was just a marketing gimmick hoping to capture unsuspecting consumers who aren’t knowledgeable enough to question their claims.

Next week we will look at ways that a Green Building can reduce its use of energy and electricity along with reducing emissions to the atmosphere.

Dan Shalloway is a Professional Engineer and a LEED Accredited Professional by the US Green Building Council. He writes a weekly column for GreenGroup.com. He is also the Developer of Florida’s first Green Industrial Park. In next week's column, Mr. Shalloway will explain how a Green Building can reduce energy and electricity and be more environmentally friendly. You can find an archive of Mr. Shalloway's columns in the Contractor's Guide.