Prospects, problems and pitfalls of urban water reuse: a case study

This paper presents a successful water reclamation and reuse project in the San Francisco Bay area. The project, which includes a water reclamation facility and a separate distribution system, is operated by a wastewater utility and reclaims approximately 4% of its dry-weather flow. Project history, its design and implementation are further discussed. Planning, and especially demand analysis, was critical for project development. Earlier attempts of water reuse were not successful because reclaimed water quality did not match the requirements of potential large industrial customers. Current customers are a mix of public, commercial and residential users who apply the reclaimed water solely for landscape irrigation. In addition, a large fraction of the reclaimed water is used internally in the main wastewater treatment plant. Early connection of largest customers, innovative collaboration with a neighboring reclamation project and cooperation of the local water supplier were very important for project success. Distribution of internal process water consumes most energy. The second major energy use is for the treatment of reclaimed water while distribution of reclaimed water to external customers requires least energy.