本研究係依據ISO 14046水足跡標準及H2〇e水足跡評估法，探討再生塑膠粒進行水足跡 評估之必要原則與方法，以獲致水足跡評估結果。H2〇e水足跡評估法結合了消耗用水與降級 用水（即品質退化之水）的潛在環境衝撃，而彙整成一個以生命週期評估為基礎之指標，稱為 產品之水足跡。本研究以一間環保局核可之廢塑膠再利用公司為個案，並選擇個案公司生產量 最多的再生塑膠粒為標的產品，亦即選擇聚丙烯再生塑膠粒進行水足跡評估。在系統邊界 上是屬於「搖籃到大門」模式，其水足跡量化包含該產品生命週期之原料取得與製造等階段， 功能單位為「一袋聚丙烯再生塑膠粒（重量為653公斤）」。本研究結果顯示，個案公司所生產 的聚丙烯再生塑膠粒每功能單位之水足跡為514.287 KLH2Oe (即514287公升H2Oe)。本文也 探討了一個節水情境，該節水情境每功能單位之水足跡為511.077 KLH2Oe，與基本情境相比， 節水情境每功能單位之水足跡減少了 3.21 KL H2Oe。

In this study, the standards of the ISO 14046 water footprint (WF) and H]Oe WF assessment methods were applied to investigate the required principles and methods for assessing the WF of recycled plastic particles. The WF of recycled plastic particles was obtained based on the relevant standards. The H]Oe WF assessment method involves combining the potential environmental impact of both consumptive and degradative water use and integrating them into a single LCA-based indicator called product WF. A real waste plastic recycling company authorized by the Bureau of Environmental Protection was examined as a case study, and the most popular form of recycled plastic particles (i.e., polypropylene (PP) recycled plastic particles) in the company was selected as the target product to assess the WF of recycled plastic particles. The system boundary was “cradle to gate,” denoting that WF quantification must include the life cycle of the products from raw material acquisition to production. The functional unit was “a bag of PP recycled plastic particles ( 653 kg in weight) .” The results of the study indicate that the WF of PP recycled plastic particles was 514.287 KL H2Oe. In addition, this study investigated a water-saving scenario, in which the WF of PP recycled plastic particles was observed to be 511.077 KL H2〇e, thereby exhibiting a reduction of 3.21 KL H2Oe when compared with the WF in the base scenario.