Measuring Sustainability of Alternatives to Use of Potable Water to Flush Toilets Using Life Cycle Assessment

The drinking water and wastewater infrastructures in the US are aging and are unable to square the mounting pressures due to degradation of pipes. There is a serious shortfall of funds between current investments and the investments that will be needed, in the next few decades, to meet mandates of Clean Water and Safe Drinking Water Acts. In addition, the current water infrastructure is very energy intensive which makes the entire process even more expensive. One solution for addressing these issues is by implementing integrated water management systems in buildings that use less potable water and send less water to sanitary and storm sewers, to benefit from the reduction of energy use to treat the amount of water being sent to the waste water treatment plants. Toilet flushing is one of the large applications of potable water. Implementation of the most sustainable alternative to use of potable water for flushing toilets ,to a large set of buildings in an area, can significantly help reduce the energy use, cost and also carbon emissions over a period of time in that area. There has been much renewed interest in this topic partially because of the popularity of the US Green Building Council's LEED rating system that includes water efficiency and sustainable sites credits to address storm, potable, and sanitary sewer water quantities. Currently, designers pick supposedly sustainable solutions for a specific building in absence of scientific data on the actual impacts and benefits of the proposed solution. The focus of this research is comparison of four alternatives to use of potable water in flushing toilets in North Engineering building at the University of Toledo. The alternatives compared are i) use of roof water to flush toilets, ii) Use of grey water to flush toilets iii) using composting toilets, iv) use of low flush toilets, based on the following criteria, a) amount of potable water being used b) energy use for operation of these systems c) Cost and energy spent on treating this amount of water, in each case, using life cycle assessment. Sustainability indicator analysis and also, the possibility of obtaining LEED credits by using each of the methods will be determined.