Irrigation accounts for a large proportion of total urban water demand. It is also a key driver of peak demand, and a significant source of urban runoff. Most studies and green industry professionals also believe that over-watering is widespread among the region’s urban landscapes. All these factors combined suggest that conservation activity in this arena is likely to yield rich dividends on a number of different fronts.
Several approaches have been tried in the past to improve outdoor water use efficiency, such as, behavior modification through education, surveys/audits, conservation rate structures, and ordinances (e.g., day-of-week irrigation limits, Model Landscape Ordinance), and through application of modern technology (e.g., weather-based controllers, drip irrigation, gray-water reuse). Strategies based upon behavior modification, or application of new technology, are by no means mutually exclusive—in fact using them in concert usually leads to significant synergies.
Our goal in this section is to summarize key aspects of what we know about weather-based irrigation controllers. Weather-based controllers attempt to match irrigation to plant evapotranspiration (ET) needs, hence they are also referred to as ET controllers. Large, expensive, ET controllers for use in commercial landscapes have been available for some time. Recently, however, smaller, inexpensive units for use in residential settings have also started to appear on the market, opening up a conservation tool that heretofore was unavailable. Several of these newer, smaller, units have been extensively field tested during the last several years. Here we summarize what has been learned through these field studies and make recommendations about how best to integrate ET controllers into the existing framework of conservation PBMPs.