Abstract: This study compares the degree of sustainability and performance across three different systems that could be practically adopted by The University of Toledo (UT) to help conserve water for future generations. The systems considered were rainwater harvesting, greywater recycling and composting toilets. Over the last decade, the role of these three systems in reducing water consumption had been widely recognized across the world and many buildings are currently using these systems either individually or in combinations. While all three systems are capable of reducing the potable water usage in toilet flushing in North Engineering (NE) building of UT, each system has its own method of water conservation. Rainwater harvesting uses the collected rainwater as an additional source of supply for toilet flushing while greywater treatment enables the reuse of treated greywater from university for toilet flushing. Composting toilets reduce the water consumption as they consume minimum amount of water per flush and no water in some cases. None of the studies so far have compared these three systems that have different ways of conserving water from a sustainability point of view and this study aims at filling this knowledge gap.

This study provides two approaches of comparing these systems. Based on the LCA and indicator analysis performed by the group, it was inferred that composting toilets were found to be the most sustainable alternative system to reduce water consumption at UT. However, it is also preferable to have greywater recycling for maximum water conservation as the grey water produced by the university accounts for almost 35% total water consumed by university.