Risk-Based Framework for the Development of Public Health Guidance for Decentralized Non-Potable Water Systems

Use of onsite water sources (e.g. roof runoff, stormwater, graywater and wastewater) to meet non-potable demands is gaining much interest. Here, these systems are referred to as decentralized non-potable water (DNW) Systems. An independent advisory panel was formed to develop guidance for DNW Systems with focus on multi-user building to neighborhood to district scale projects. The DNW Systems framework includes risk-based guidance based on estimated pathogen log reduction targets (LRTs) for various source waters and end uses. The intent of this framework is that the approach can be applied to expand to multiple water sources and end uses of interest, and that this framework will serve as a basis to address those sources and end uses currently covered. This paper presents an example application of the DNW System framework to design a DNW system and specify the management and monitoring requirements for that system.