Home\Educate\Water Reuse 101\Research Projects\Year\2015\Framework for Informed Planning Decisions Regarding Indirect Potable Reuse and Dual Pipe Systems

Framework for Informed Planning Decisions Regarding Indirect Potable Reuse and Dual Pipe Systems

Project: 09-02
Type: Decision Making Tool
Year Released: 2015

Program: Principal
Total Investment: $415,232 (Cash: $250,000, In-Kind cash and service: $165,232)

Principal Investigator: Guy Carpenter, Carollo Engineers


Reclaimed water can be deployed for irrigation or non-potable uses through piping systems separate from potable water called dual pipe systems (NPR). Reclaimed water can also be stored in aquifers or surface water bodies, which supply potable water systems (IPR). This project developed a decision support tool that incorporates drivers and constraints of  NPR and IPR alternatives with financial, social, and environmental criteria through a Triple Bottom Line (TBL) approach to deploying reclaimed water resources.

Goals and Objectives

The goal of the projects is to produce a decision making tool that would facilitate informed, defensible decisions regarding capital investments for non-potable reuse (NPR) or indirect potable reuse (IPR) alternatives at municipal and regional planning levels.

The objectives are to:

  • Incorporate data from utility surveys in the decision tool,
  • Incorporate non-financial goals and criteria into the decision process,
  • Keep the decision process transparent and therefore more easily defensible, and
  • Make the decision tool user friendly.

Research Approach

The utility surveys were designed to obtain information about current/planned water reuse programs, restrictions/limitations in using reclaimed water, financial metrics, regulatory requirements, public support or opposition to water reuse projects, service goals and political issues, to name a few. The results of the survey were complied to provide the framework for the decision tool development.

The decision tool developed allows the user to identify drivers for water reuse, complete a feasibility analysis for NPR and IPR, and compare up to 6 water reuse alternatives in a TBL analysis.

Findings and Conclusions

  • The use of reclaimed water (both NPR and IPR) provides enhanced flexibility for water resources management.
  • Long-term water scarcity, short-term drought impacts, and wastewater management considerations were the primary drivers for implementing water reuse (both NPR and IPR).
  • Historically, political issues have impeded or prevented IPR projects, but politics were not a hindrance for the 14 agencies that participated in this project.
  • IPR and NPR strategies are not mutually exclusive, and many of the agencies surveyed are using elements of both approaches.
  • Constraints specific to the agency are the driving force in selecting between NPR and IPR and typically include cost, regulatory issues, and water quality impacts.
  • In some cases, water rights were an obstacle in pursuing IPR strategies.
  • Public opinion was not identified as an obstacle to IPR by the participating agencies in this project.

Cost was not an identifying factor in the selection of NPR or IPR strategies, although it is an important criterion by which projects are judged.

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