Environmental Science and Engineering Magazine. November 2011
Household water usage is declining slowly but steadily, a trend that is expected to continue for at least the next 15 years. This is good news in light of the challenges some areas face in managing this essential resource. At the same time, it presents a challenge to water utilities, which must adapt their systems and rates to reduced consumption trends, in order to cover fixed costs and maintain reliable service.
A 2010 study by the Water Research Foundation concluded that “a pervasive decline in household consumption has been determined at the national and regional levels.” As reported in Journal AWWA, the study, which tracked trends in household water use in North America over the past 30 years, found that “a household in the 2008 billing year used 11,678 gallons less water annually (13%) than an identical household did in 1978.”
This finding is supported by the experience of American Water, which serves approximately 15 million people in more than 30 states and parts of Canada. In its 2010 annual report, the company reported a declining trend in residential water usage for all of its regulated states, in the range of 0.5–2% annually over the last 10 years.
Monthly analyses of residential sales across its largest state subsidiaries from 2001 to 2010 reveal an annual decrease of 1–2% (based on gallons/customer/month). These subsidiaries service a wide range of household demographics in climates that span from arid to water-rich, providing a broad base by which to assess water usage trends.