Application of the Integrated Urban Water Model to Evaluate Impacts of Hydrology on Efficacy of Water Conservation Practices

The challenges of addressing the needs of aging water and wastewater infrastructure require new management approaches. Benefits including water savings, cost savings, and reduced wastewater production may be realized through the adoption of new integrated water management concepts such as treated wastewater effluent and/or graywater reuse, rainfall harvesting, etc. Determining which water management practices are best suited to a particular urban area can be a difficult task as costs, climate, and population characteristics vary across regions. The Integrated Urban Water Model (IUWM) has been developed by the Urban Water Center at Colorado State University to aid urban planners and utility managers in the assessment of which water management practices may prove most beneficial to their communities. These practices include: indoor conservation, irrigation conservation, wastewater treatment plant (WWTP) reuse for irrigation, graywater reuse for toilet flushing and irrigation, and stormwater capture reuse for irrigation. IUWM was applied to five cities in different climatological regions of the United States. These cities are: Fort Collins, Orlando, Philadelphia, San Diego, and Seattle. The example applications serve as both an example of how IUWM might be applied and explores the effectiveness of combinations of water management practices in different hydrologic regions. The results of the example application study confirm that hydrologic conditions impact the effectiveness of selected water management practices. In locations with limited rainfall, there is limited benefit to collection of stormwater for irrigation. Large water savings can be achieved from practices that reduce irrigation demand in locations with high irrigation demand. Aside from implementation of indoor and irrigation conservation practices, graywater reuse displayed the greatest cost savings for the cities included in the study. This is a result of decreased wastewater production associated with graywater reuse.