NYC Nonpotable Water Systems Guidance on Design, Operations, and Public Health Protection

[b]Summary:[/b] New York City (NYC) is increasing awareness and adoption of decentralized non-potable water reuse through a newly developed Guidance Manual. While traditionally associated with water-stressed regions, NYC is reframing water reuse as a proactive tool for urban resilience, infrastructure relief, and sustainable design. The Guidance Manual, developed for a broad range of stakeholders, outlines implementation pathways for building- and district-scale systems, addresses multiple water sources, including graywater, blackwater, rainwater, stormwater, and clear water waste, and defines approved end uses, treatment requirements, and public health protection measures. Drawing from national best practices, the Guidance Manual includes a critical control point approach, microbial log removal targets, and risk-based water quality standards. It also emphasizes operations and maintenance planning. Developed in collaboration with various city agencies, this Guidance Manual provides a practical, public health-protective model that other urbanized areas may follow as they look to integrate recycled water into their water management portfolios. [b]Learning Objectives:[/b] Attendees will learn about NYC's first Guidance Manual for decentralized non-potable water reuse, which identifies relevant system types, applicable water sources and end uses, treatment requirements, and associated benefits. The presentation will cover fundamental principles for public health protection, including microbial log removal targets and the use of a critical control point framework. Participants will also gain insight into how the Guidance Manual balances operational feasibility with health protection and reflects interagency collaboration. NYC's approach will be highlighted as a forward-thinking model which other urban areas could reference when integrating recycled water into their water management strategies. [b]Full Abstract:[/b] Non-potable reuse holds a strong and growing position as an arrow in the quiver of optimizing water supply and taking pressure off precious water resources. Further, decentralized systems, which may not benefit from economies of scale relative to larger centralized systems, reap other significant advantages which drive their adoption, including reducing strain on local conveyance infrastructure. New York City has supported decentralized non-potable water reuse for years, with buildings like the One World Trade Center investing in such systems, and citywide reuse efforts helping to reduce combined sewer overflows (CSOs). While non-potable water reuse is often associated with water-stressed regions, its emergence in water-abundant cities such as NYC marks a novel and forward-thinking shift - one that reframes water reuse not as a necessity born of scarcity, but as a proactive tool for urban resilience, infrastructure relief, and sustainable design. To increase awareness and adoption of non-potable water reuse in NYC, a visually engaging Guidance Manual has been recently developed for a broad range of stakeholders, including developers, owners, engineers, and building maintenance staff, that outlines decentralized reuse options and provides a clear pathway for implementation. The Guidance Manual considers two options for decentralization – multi-unit apartments or commercial type buildings and broader district scale systems – with tailored requirements for each. In addition to blackwater and graywater uses, the Guidance Manual also considers rainwater (precipitation collected on a roof surface), stormwater (precipitation collected below a roof surface), clear water waste (drips from equipment such as condensate) and foundation drainage. For each source of water, approved end uses, along with corresponding treatment and public health protection measures, are also outlined. The Guidance Manual provides a holistic review of engineering design plans of systems including identification of sources, identification of end uses, determination of treatment requirements, definition of startup up and validation requirements, and description of a final ongoing monitoring plan. Leveraging from the National Blue-Ribbon Commission for Onsite Non-Potable Water Systems, water quality requirements are considered not only in terms of a final treated water quality, but also in terms of microbial and chemical risk. Using a critical control point approach, the Guidance Manual outlines specific microbial log removal requirements alongside the microbial log removal achievable for treatment trains to ensure public health protection. The development of operation and maintenance plans are also discussed, with a balance struck between practical operational constraints and maintaining public health as paramount. This approach is expected to serve as a model for other urbanized areas to integrate recycled water into their water management portfolio. This presentation will outline the Guidance Manual developed to encourage decentralized water reuse systems in NYC. It also highlights the collaboration between the NYC Department of Environmental Protection and the NYC Health Department, which together have created a practical pathway that encourages system development while ensuring environment and public health protection.