Consulting-Specifying Engineer - March 2009 - (Page 19) Codes & Standards Using gray water efficiently Engineers may face roadblocks when designing gray water systems, but the technique is gaining traction. BY AMARA ROZGUS, Senior Editor ost engineers focus on lighting, HVAC, windows, and building siting when designing an efficient building. Often secondary on the list is designing a water-efficient building, which can be accomplished with various methods like no-water urinals, dual-flush M Building inspectors often have limited knowledge of gray water plumbing codes, a big barrier to plumbing engineers. water closets, and water reclamation, i.e., harvested rainwater and gray water. It’s sometimes referred to as graywater or grey water. Whatever you call it, it generally consists of reusing water originally used for hand-washing. What are the codes governing the use of reused water? That’s where the issue becomes, well … gray, and many engineers meet a roadblock in either materials funding or local building codes—or both. The 2009 International Plumbing Code Appendix C is the guideline provided to jurisdictions that adopt this plumbing code. Appendix O of the International Residential Code is quite similar, though only for residential dwellings. The first problem, funding, is the biggest push-back an engineer might receive from a building owner or management firm considering a whole-building gray water system. A whole-building system requires two sets of piping: one for fresh, potable water, and the other for gray water. A double-pipe system can double the materials cost. Plus, putting in place a cistern or other device to store the gray water ADDITIONAL READING 2009 International Plumbing Code: www .iccsafe.org Gray Water Policy Center, Oasis Design: http://oasisdesign.net /greywater More suggestions and links to local codes are online at www .csemag.com/graywater requires both space and money. Unless the gray water can be moved by gravity to the place it’s eventually used (such as for outdoor irrigation), pumps must be installed to move the water, especially if the water is being pumped to a multistory building for use in something like a cooling tower. Finally, many authorities having jurisdiction (AHJ) want the gray water treated before it’s reused with a tertiary treatment such as a filter, chemical treatment, or ozonation. Most authorities (and building residents) don’t want untreated—and possibly smelly or filmy—gray water sitting around in a storage tank for too long. Plumbing engineers unfamiliar with nontraditional plumbing designs, equipment, and code issues may run into trouble, possibly with the health department. Local health departments often voice their concern that the gray water might have a cross-connection with potable water, and even a connection to public water. AHJs typically don’t want the water sitting for more than 72 hours, and many have maximum amounts that can be stored at any time. To add to the cost, the gray water influent pipe and the drain to the jurisdiction’s sanitary sewers must be the same size and meet local code. Meeting with the locals Building inspectors often have limited knowledge of gray water plumbing codes, a big barrier to plumbing engineers. Water reuse is common and much-needed in the West, so gray water and rainwater use is more common. Engineers, Consulting-Specifying Engineer • MARCH 2009 19 http://www.iccsafe.org http://www.iccsafe.org http://oasisdesign.net/greywater http://oasisdesign.net/greywater http://www.csemag.com/graywater http://www.csemag.com/graywater
For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.