Discussion and conclusion
This research demonstrates the coupled role of urban form and sociodemographic characteristics in water use and drought-related conservation behavior. A crucial finding of this study is the importance of the built environment when classifying urban water customers and creating residential neighborhood typologies useful for water use and conservation analyses and developing demand management strategies. Traditionally, many researchers have stratified customers by income, finding that affluence is associated with high water use, high levels of drought-related conservation, and subsequently high conservation backslide post-drought. These water use characteristics are typically linked to more wealthy customers having bigger lots and therefore using more water outdoors. However, this study proves that income does not always correlate to high water use, and that affluent residents choosing to live in dense, new developments have very different water use patterns and water use behavior.

We bypassed previous data constraints faced by researchers, utilities, municipalities and other public agencies trying to better understand how built environment factors are linked to water use by utilizing data from an online real estate aggregator. By obtaining customer-level information from the Zillow ZTRAX database, this research for the first time demonstrates the possibility for this kind of platform to serve as a new tool for incorporating housing features into water use analyses. City and county assessors are legally required to fulfill public record requests and provide data in response to inquiries, but acquiring these individual datasets for comparative regional, state, or national assessments can be prohibitive. Thus, using aggregated data generated by Zillow and similar websites can provide a gateway for widespread analyses, for example opening the door for multi-city or even multi-state studies. These new websites offer a way to access built environment data uniformly in one place instead of filing separate records request for each service area of interest. While this research presents an alternative to traditional methods for obtaining information about the built environment, water use data remains sparse and challenging to acquire (Chini and Stillwell 2016, Josset et al 2019).

As this is the first research to use Zillow in water demand research, there are a host of avenues for future research. For example, our study was set within one utility, but the potential for Zillow truly lies in its ability to cross administrative borders. For example, where cross-city and multi-city comparisons in different counties previously required obtaining data from each individual jurisdiction, Zillow or other online aggregators store this data in one central location. Having one central database also provides the benefit of data consistency.

Additionally, here we focused primarily on neighborhood clustering to inform residential water use modeling at the monthly scale, but future studies could explore how emerging databases, online platforms, and data aggregators with high spatial and/or temporal resolution can be coupled with higher temporal resolution water use data from smart meters to better understand and predict water use and conservation. These insights could then be used to develop short-term and long-term demand management strategies. Another avenue for future research would be to investigate how different emerging urban form paradigms including infill development, peri-urban, and suburban designs shift both short- and long-term water use behavior. Land managers and water managers often do not coordinate or even talk to each other (Gober et al 2013), but with these new developments and unprecedented urbanization, there is increasing pressure for integrated planning and management.

This research lays the framework for future big data-driven urban water research and provides evidence for the implications evolving urban form on water use. Our results also point out future paths of more water-efficient urban development. Cities all over the world are expanding at rapid rates, and there are many different ways for them to develop. Here, we showed that dense housing patterns and new houses, regardless of the size, can result in lower water use than traditional sprawl. However, these low water use communities also have lower conservation rates and sometimes faster post-drought water demand rebound, and actions must be taken to account for this reduced water system flexibility. City planners and water managers must work together to develop cities of the future that house an increasingly large portion of the population and meet the wide-range of sustainability-oriented goals critical to addressing 21st century urban challenges.

Good stuff!


"You can't teach an old dogma new tricks." - Dorothy Parker (quoted in @TheMVTimes via @TheWeek)