Drought Watch: Trends in Urban Water Use

By Emma Freeman, Caitrin Chappelle.

Most of California is now in an exceptional drought, but water use statewide has actually increased over the last year. In response, the state has imposed short-term restrictions intended to help us get through the current drought. As state and local water agencies look beyond the current emergency for ways to adapt to a future in which droughts are likely to be more frequent and more severe, it is instructive to examine and compare urban use in two relatively normal water years, 2000 and 2010.

First, the good news: Total statewide urban water use (for residential, commercial, and industrial purposes) decreased by 12 percent from 2000 to 2010, even as California’s population increased by more than three million. Reductions have been especially significant in central and southern California, where investments in conservation programs and new technologies seem to be paying off. In the commercial and industrial sectors, water use fell 36 percent and 18 percent, respectively, while residential interior water use declined by 20 percent overall and 27 percent per capita. The Great Recession probably played a role in these reductions, so it will be interesting to see if this trend holds as the economy continues its recovery.

Now for the bad news: Outdoor water use for both residential exteriors and large (commercial or public) landscapes rose 12 percent across the state between 2000 and 2010. This trend was largely driven by increases in southern California—in marked contrast to the region’s reductions in indoor water use. And it is likely to persist as California’s population continues to grow, especially in hot and arid inland areas with a higher proportion of single-family homes (which use twice as much water outdoors per household as multi-family buildings) and large lots.

One important takeaway is that more stringent building codes, increasing efficiency requirements, and new technologies seem to have resulted in more efficient indoor water use. But when it comes to landscaping, any improvements in irrigation technology seem to have been offset by our taste for large lawns and plants that need a lot of water (and our habit of overwatering them). To encourage long-term reductions in outdoor water use, agencies can implement new pricing structures, turf buy-back programs, and public education programs emphasizing drought-friendly landscaping. After our current water emergency ends, these long-term incentives and outreach efforts can help us be better prepared for future droughts.

(The map below shows the change in per capita outdoor urban water use between 2000 and 2010 in each hydrologic region. To see details of the state’s hydrologic regions, including county boundaries, visit our Map Room.)