Date of Award

Spring 2020

Project Type


Program or Major

Civil Engineering

Degree Name

Master of Science

First Advisor

Weiwei Mo

Second Advisor

Kevin Gardner

Third Advisor

Kyle Kwiatkowski


With populations rising and increased urbanization, water stress and water shortage have become more common in cities across the US. Incorporating decentralized water systems into today’s largely centralized water systems has been considered as a potential means to reduce a family’s residential water footprint and provide an economic benefit over time. However, our understanding regarding how different decentralized water systems compare to each other when installed in different types of buildings under different geospatial and climate conditions remain limited. This study considers implementing greywater recycling (GWR) and rainwater harvesting (RWH) systems in two different household sizes in 12 different cities within the United States. Each city has different characteristics to consider, such as precipitation dynamics, irrigation periods, and utility rates. This investigation calculates the percent of water that meets the demand of a household and the total economic savings/payback time as a function of tank size to achieve the optimum benefit of each system type using a systems dynamics model with a daily time step. We found that for GWR, cities had optimum tank sizes of 2-3 m3 for multi-family housing and 0.75-0.85 m3 for single-family housing. Demand met for GWR ranged from 70-90%, while RWH ranged from 50-70% across all cities. Optimal tank sizes for RWH ranged from 5-10 m3 for multi-family housing and 4-6 m3 for single-family housing. Overall, Boston, Seattle, and Atlanta performed the best for both GWR and RWH, single-family and multi-family, in terms of payback and demand met.