Cross-connection testing methods are similar in most jurisdictions and are based on the UPC and other standards, such as the EPA's Cross- Connection Control Manual.
Piping and materials
When selecting materials for greywater collection and distribution piping, the engineer needs to consider code requirements along with cost and constructability. Greywater collection piping typically matches the piping used for the building's sanitary waste, typically PVC or cast iron. Both materials are suitable and offer pros and cons that must be evaluated. Nonpotable and reclaimed water distribution piping is available in a multitude of options. Copper, PEX and CPVC are all suitable choices; typically, they are provided in purple to distinguish them from a buildings' potable water system. Pipe labeling requirements can be found in Chapter 6 of the Uniform Plumbing Code; it is important to verify if your local AHJ requires any additional modifications.
Maintenance
Maintenance needs vary greatly, depending on the size of the greywater system, but annual and preventative tasks are needed for all systems. The primary maintenance needs are inspection and cleaning of filters. Additional requirements are listed in Figure 6 from the UPC, ranging from water quality testing to cleaning the greywater treatment tank.
Water savings
Along with lower-flow and -flush fixtures, targeting LEED certification can use greywater reclamation to realize additional water savings. The calculation in Figure 7 shows the potential water savings that can be achieved by combining these two methods. The extra water savings boost from greywater harvesting allows the maximum number of LEED credits to be reached, including bonus points for regional priority and exemplary credits. Compared to other building design choices to maximize LEED credits, such as glazing and high- efficiency HVAC systems, greywater reclamation can provide as much or more value for a building's owner. As water and sewer rates continue to increase, the system can provide long-term savings and payback of the initial investment.
Codes and standards
As is the case for plumbing codes across the United States, there is not a singular nationally accepted greywater harvesting standard. In the absence of a national standard, many states enacted their own regulations through local health departments, while others adopted standards such as NSF/ANSI 350: Onsite Residential and Commercial Water Reuse Treatment Systems or IAPMO IGC 324: Alternate Water Source Systems for Multi-Family, Residential, and Commercial Use. While these references are not adopted in all jurisdictions, their requirements should be used to create a baseline system design relating to water treatment and quality as well as public health concerns. l Jonathan Franzese is a Senior Engineer and the Plumbing Engineering Manager at McKinstry in Seattle. He currently serves as the ASPE Seattle Chapter President and is a member of ASPE's Credentialing and Education Committees.
GREEN SYSTEMS
170
phc May 2022 www.phcppros.com Figure 6: Typical greywater maintenance schedule (UPC Table 1501.5). Photo: Uniform Plumbing Code Figure 7: LEED calculation with greywater. Photo: McKinstry Co.
The extra water savings boost from greywater harvesting allows the maximum number of LEED credits to be reached, including bonus points for regional priority and exemplary credits.
Previous Page