Article | June 2, 2021

EPA Researchers Develop Tool To Assess Onsite Non-Potable Water Reuse For Buildings Across The U.S.



Increasing pressure on water resources has led to greater water scarcity and a growing demand for enough clean water. Many communities across the country have initiated, or are in the process of developing, centralized systems for planned water reuse. Water reuse is the concept of intentionally recycling, treating, and reusing alternative water sources. Federal government agencies and the water user community are coordinating their efforts to advance the adoption of water reuse and ensure the security, sustainability, and resilience of water resources. The National Water Reuse Action Plan (WRAP) describes these collaborative actions.

Highlighted in the WRAP, onsite, non-potable reuse is a strategy that could help communities recycle and reuse water for non-drinking purposes. This approach is increasingly being considered as one of the most viable options to address water scarcity and infrastructure challenges, such as reducing costs and pollutant amounts, particularly for individual buildings. Onsite non-potable water systems collect and treat water sources from within, or surrounding, a building, such as stormwater and wastewater. The captured water can be treated and reused locally or onsite for toilet flushing, clothes washing, plant irrigation, or other non-drinking purposes.

The implementation of non-potable water reuse can vary greatly among geographic locations and building types. To assist with these variabilities, EPA researchers developed the Non-Potable Environmental and Economic Water Reuse (NEWR) Calculator.  NEWR is a web-based tool designed to provide screening-level assessment for any urban building located across the United States. It provides a comprehensive integrated assessment of treatment options, onsite non-potable demand, the environmental impacts, and costs.

NEWR allows users –communities, states, city planners, building designers, water resource organizations, or utility personnel - to identify the most environmentally and cost-effective suite of source water options to meet non-potable needs while taking into account the geography, climate, energy grid, building size, and building type.

The Calculator uses life cycle costing and life cycle assessment to calculate economic cost and environmental impacts associated with onsite source water options including rainwater harvesting, air-conditioner condensation harvesting, and treatment of source-separated graywater or mixed wastewater using a membrane bioreactor.

Building operators can use NEWR to make an informed, balanced decision on non-potable water reuse, balancing public health protection, for example reducing pathogens, with environmental and economic performance in a holistic analysis focusing on resilience and sustainability. The Calculator also helps avoid or optimize the weaknesses in systems, for example a process that may be energy intensive. This tool can help a community transition towards the adoption of innovative technologies like onsite water reuse while considering issues that are unique to their cities or communities.

Cissy Ma, an EPA researcher and one of the NEWR project leads, worked with partners and colleagues to explore the quantification of life cycle impacts and costs to build the business case for non-potable water reuse implementation.

“The water crisis in Texas with damaged water infrastructure after the recent severe winter storm is the latest somber reminder that we need to rethink our water systems and learn how to be resilient to disasters like this and the climate change impacts of the future,” stated Cissy.  “Decentralized non-potable water reuse can be one of the alternative options.”

Water reuse strategies are not just related to water quantity, but also the water quality, the treatment required for safe water, the cost of installation and operation and maintenance, avoided drinking water costs, and avoided energy use for potable water treatment and distribution. Integrated assessment metrics are needed to capture the complexity of non-potable water reuse implementation.

“NEWR fills the gap and provides a tool for users to explore different options and helps catalyze some of the first steps of transformational changes in water systems,” stated Cissy.

Building owners, operators, city planners, or any water professionals interested in understanding the economic costs and environmental benefits of their water options can view the new NEWR calculator.

EPA worked with San Francisco Public Utilities Commission to help achieve their onsite non-potable water reuse systems goals by using their data to answer questions. Based on the data from San Francisco, EPA researchers developed and expanded NEWR. In addition, groups including Austin Water, U.S. Green Building Council, Canadian Green Building Council, American Rainwater Catchment Systems Association, and the City of New York, have contributed to testing the tool, or have used it for their water reuse efforts.

Learn more:

Water Reuse Research

Onsite Non-Potable Water Reuse Research

NEWR Calculator