The distribution of reclaimed water using dual water distribution systems, one for potable water and the other for nonpotable water, is a widely accepted practice. Some drivers for the increasing use of reclaimed water include diminishing supplies of high-quality water resources, escalating costs for developing new sources or for treating poor-quality water to potable-water standards, and the increasing costs involved in discharging wastewater to the environment.

M24 provides the latest information for water systems wishing to distribute reclaimed water. This manual discusses the planning, design, construction, operation, regulatory framework, and management of community dual water distribution systems, which consist of separate systems for distributing potable water and nonpotable water principally drawn from reclaimed wastewater specifically for use in such dual distribution systems.

This fourth edition contains considerable revision, most notably the incorporation of the USEPA 2012 Guidelines for Water Reuse and 2017 Potable Reuse Compendium. Additional changes that reflect advancements in the field have also been incorporated throughout the manual.