The Flaw with Per Capita Water Use


DSCF0032Curtailed water use and conservation are common topics of conversation in areas with water supplies limitations.  As drought conditions worsen, the need for action increases, so when creating a regulatory framework, or when trying to measure water use efficiency, water supply managers often look for easily applied metrics to determine where water use can be curtailed.  Unfortunately, the one-size-fits-all mentality comes with a potential price of failing to fully grasp the consequences decision-making based on such metrics.

One of the issues that water supply regulator like to use is per capita water use.  Per capital water use is often used to show where there is “wasted” water use, such as excessive irrigation.  However such a metric may not be truly applicable depending on other economic factors, and may even penalize successful communities with diverse economic bases.  A heavy industrial area or dense downtown commercial center may add to apparent per capita use, but is actually the result of vibrant economic activity. Large employment centers tend to have higher per capital use than their neighbors as a result of attracting employees to downtown, which are not included in the population.

In south Florida, a recent project I was involved with with one of my students showed that while there was significant variability among utilities, but the general trend of increased economic activity was related to increased per capita use.  Among the significant actors were health care, retail trade, food service and scientific and technical services.  It appears to be these sectors that drive water use upward.  As a result when evaluating the efficiency of a utility, an analysis should be conducted on the economic sectors to insure that water regulations do not stifle economic growth and jobs in a community.   And conversely if you do not have these sectors, you water use should be lower.  Something to think about when projecting or regulating water use.  Limited water use may in fact be limiting economic activity in the area. Of course if you are water limited, limited new withdrawals may be perfectly acceptable if you want to encourage other options, like direct or indirect potable reuse, irrigation, etc.  

It would be interesting to expand this study across the country to see what the national trends look like and how different tourism oriented South Florida might actually be.

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