Recent trends in water demand are challenging some long-held assumptions of Southwest municipal providers and planners.
September’s AHS symposium focused on “recalibrating the hydrologic approach,” challenging participants to question some of their long-held beliefs about water. The first plenary session (which featured Grady Gammage, Jr., and M&A’s Gary Woodard) explored how existing assumptions can lead water resource professionals astray.
Recent trends in water demand underscore this point. Historically, water providers have pegged their demand forecasts to population projections. But for decades now, many providers in the Southwest have experienced flat water demand (more or less), despite rapidly growing service area populations.
The reason for this decline is simple: per-household demand has dropped significantly. However, the factors behind the decline are complex. These factors have been the subjects of various research efforts, including an M&A-led study in Pima County. Although many questions remain, a number of key findings have emerged:
- Population growth is no longer the principal driver of water demand.
- Existing homes are becoming significantly more water-efficient over time.
- The resale of homes and “house flipping” has hastened the replacement of old, inefficient fixtures and appliances.
- New homes are much more water-efficient. More national builders are touting the sustainability and efficiency of their new models.
- Appliances and fixtures have become significantly more water efficient. This trend will continue; it is driven not by mandatory federal standards, but by market demand and voluntary standards, such as WaterSmart and ENERGY STAR.
- Backyard swimming pools are scarcer. New pools are, on average, much smaller.
- Our love affair with lawns is over. Turf areas have been reduced, overseeding with winter rye is less common, and artificial turf is gaining popularity.
- Income no longer correlates with greater water consumption. Wealthier households eschew evaporative coolers, buy high-end front-loading washers, and remodel kitchens and baths with more efficient fixtures.
Many factors underlie the declines in residential water use; however, it seems clear that household demand will continue to decline for years to come. Since the consequences for water providers, wastewater providers, and water planners are significant, developing a better understanding of the relationship between the various demand factors is critical.