12.02.2012

Micro Intervention: Urban Rainwater Harvesting

Photo courtesy of  aia.org
Australian inventor and architect Sally Dominguez's invention, the HOG system makes use of otherwise overlooked spaces for use as rainwater harvesting.  

The American Institute of Architects (AIA) reports that the inspiration for Dominguez’s rainwater harvesting system came to her while working on residential infill projects in inner-city Sydney. As a city on the edge of literally running out of water, it is no surprise that such innovations are spun from Australia.  Discouraged by the lack of small-scale solutions for stromwater storage, Dominguez  wanted to look beyond  the existing large-scale solutions the city has been exploring in recent years, (1)


Photo courtesy of aia.org
The HGO is a water storage system that makes use of spaces that are largely overlooked: underneath floors, inside walls, and along narrow alleys. She solved the problem of how to make flat-walled steel tanks fit in those spaces without bulging with the weight of their water by placing a hole in the middle of the container. In this way, the hole’s circular walls act as an inside-out brace (see below).It helped that Dominguez had some prior product development experience, and knew that the manufacturing method known as “rotomolding” (rotational molding) worked well for creating hollow plastics — and might apply equally as well to creating modules that could stand on any of their sides and join conveniently to the next one. Using this method, she created a highly scalable water storage system that can easily link one module to the next while allowing water to flow through them without impediment. (1)

The first Rainwater HOG tank debuted in Australia back in 2005, at a time when rainwater was still considered gray water (i.e., used household water). Thus the name: H2O Grey, or H2OG, or HOG. Now a version of the tank manufactured in the U.S. is available to the U.S. market, where the system has gained widespread popularity among green builders and architects in recent years.  (1)

We thought this was interesting in its potential application in places like Philadelphia and other large cites on the East Coast that are struggling to meet the EPA requirements for combined water/sewer outflows (CSO).  Obviously there would need to be a way to completely drain and bypass these during the winter months, but it is nothing that a little engineering can't handle.   Like many complicated urban problems, these tanks are far from a complete solution, but represent a step in the right direction.


Photo courtesy of aia.org
Photo courtesy of aia.org
Works Cited
(1) earthtechling.com 
Thanks to JTLA for the heads-up on the story

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