Last week, while attending the 12th Annual WateReuse Symposium in Phoenix, AZ, I sat in on a series of presentations grouped under the heading “It’s Not Easy Being Green.” The presenters included Don Vandertulip (CDM), Andrew Salveson (Carollo Engineers), Paul Fesko (City of Calgary) and Ryujiro Tsuchihashi, (AECOM), and all of them spoke about the standards, schemes, and strategies associated with integrating water reuse into a community water resource plan.
In a presentation entitled “Can We Support a National Water Utility Pipe Color Code,” Vandertulip discussed the lack of a national standard pipe color standard in relation to the types of water flowing inside (potable, reclaimed, etc.), and the growing need to unify disparate standards as water reuse increases and expands—particularly as these standards relate to onsite and offsite water use. In the presentation’s white paper, Vandertulip highlights the need for consistency: “While 50 individual solutions might control local concerns, there is a benefit to the mutual designation of pipe color codes on national basis that are consistent on both sides of the property line.” Ultimately, he argues that in the interest of clarity and ease of implementation, it makes sense to use purple pipe as an indicator for reused water for both offsite and onsite plumbing. Aiding that effort is the USGBC’s LEED certification process, which includes “a uniform measure of energy and water efficiency components.”
Salveson discussed another aspect of the conflict between indoor plumbing codes and water reuse in his presentation entitled “Treating Graywater to Title 22 Standards in San Francisco.” Under current California plumbing codes standards (CPC 16S), “untreated graywater can only be used for subsurface outdoor irrigation or disposal. If graywater is to be recycled for unrestricted use (toilet flushing for example), it must be treated to meet the uniform criteria for disinfected tertiary recycled water as provided by California Code of Regulations, Title 22.” Title 22 standards require that total coliform organisms be less than 2.2 MPN/100 mL along with a 5-log virus reduction (99.999% removal). The good news it that in order to meet Title 22 standards, Salveson and his research team found that commercial graywater (comprised primarily of sink and shower effluents) need not be treated beyond filtration and disinfection, which, in turn, “results in relatively low treatment equipment cost (< 20%) compared to conventional reclamation treatment.” UV and bulk sodium hypochlorite were found to be the most cost effective treatment processes.
For the City of Calgary, AB, limited water resources forced the city to develop a detailed water resource management roadmap to establish “a framework of sustainable water management” that will “serve as a model for meeting all future water demands.” After evaluating a variety of scenarios, the City developed the following plan: accommodate future water demands using the same amount of water from the Bow and Elbow Rivers as was diverted in 2003; minimize stormwater runoff through “the implementation of LID principles;” address economic and societal issues as they relate to smart growth and local commerce; and meet new water demands “through an integrated planning approach that includes the use of potable water and nonpotable sources.” In his presentation, “Defining Sustainable Water Management in Calgary Through Truly Integrated Water Resources Planning,” Fesko and his team outline 11 steps to help the city implement a water reuse program, including: reviewing all the legal, environmental, and institutional issues surrounding reuse, refining, and comparing demand; developing a public outreach program; preparing a distribution system and determining the cost; and “integrating water utility practices into appropriate City business practices.”
In “Fit-For-Purpose Water Reuse Schemes for Sustainable Potable Water Substitution,” Tsuchihashi and his team discussed water reuse in the Victoria Central Region of Australia. In an effort to combat chronic water shortages in the traditionally arid region, the Victorian Government’s Central Region Sustainable Water Strategy (2006) called for metropolitan water authorities within the region to “invest in water recycling projects aimed at achieving 20% recycling by 2010, and set a target for potable water substitution by recycling and stormwater reuse.” Three treatment plants were initially identified, and teams set about to meet the technical challenge of designing “fit-for-purpose” treatment systems that are tailored to meet the quality requirements and demand/supply issues of each area. Both the Pakensham and Somers RWTPs will begin delivery recycled water by 2011, while the Mt. Martha TTP should be commissioned in 2012/2013. Combined, the three plants are expected to deliver a significant amount of supplemental water to the region.
So what do you think? Are the benefits of reused water enough to justify navigating a complicated initiation and integration process? Can standardization and transparency help ease the process? And what can be done at a local and national level to encourage and expand water reuse and reclamation in arid, water short regions around the country?