Employing multi-criteria decision analysis to select sustainable point-of-use and point-of-entry water treatment systems

Point-of-use (POU) and point-of-entry (POE) drinking water treatment systems are gaining prominence, particularly from the point-of-view of technical appropriateness and consumer acceptance. They are becoming an increasingly viable alternative for small water treatment systems or in individual homes. However, sustainability concerns have been voiced in a number of studies investigating these devices. In this paper, sustainability is examined with respect to the fulfillment of treatment systems for a set of technical, economic, environmental and socio-cultural objectives. Consequently, the use of a hierarchy of sustainability indicators to compare various POU and POE water treatment alternatives is proposed. The indicators' definitions, as well as calculation and normalization methods are explained. The paper also presents a decision model that is capable of selecting the most sustainable treatment option. The model employs the analytical hierarchy process (AHP) to help in the analysis of indicators' relative importance with regard to sustainability and to develop the indicators and criteria weights required for aggregating a sustainability score. The generated sustainability scores essentially level the playing field when comparing POU and POE systems for technical and economic appropriateness for a particular water treatment case, in addition to incorporating more difficult to quantify system traits, such as environmental and socio-cultural sustainability.