This document provides guidelines for evaluating the performance of treatment systems on the basis of greenhouse gas (GHG) emissions.

In order to estimate greenhouse gas emissions from a treatment system, this document covers the estimate, types of GHG emission and sources, emission factor for each GHG, and global warming potential. The weight of greenhouse gases to be used in an evaluation is equivalent to emissions during operation of a treatment system.

This document also defines a method for calculating carbon dioxide equivalent (CO_2eq) emission intensity, in which GHG emissions are divided by the volume of reclaimed water. It also includes a method for evaluating the performance of a treatment system using CO_2eq emission intensity.