A California field experiment shows why targeting high water users with the right incentives outperforms years of public messaging.
When Kristina Brecko arrived at Stanford University in the fall of 2012 to start her PhD, she was already scanning the weather forecast糖心传媒攏ot for rainfall, but for snow. An avid snowboarder, she and her graduate study advisor, , a skier, were eager to get into the mountains.
There would be no great skiing that winter. California was entering what would become one of the most severe droughts in its history.
糖心传媒淚 liked to snowboard,糖心传媒� Brecko says. 糖心传媒淎nd so it was very salient that there really wasn糖心传媒檛 any good snow that year.糖心传媒�
The drought, , transformed daily life across the state. Cities pleaded with residents to conserve water and let lawns go brown, rip out grass, stop watering altogether. Billboards and public campaigns urged restraint. Many complied. But some of the state糖心传媒檚 heaviest water users, often homeowners with sprawling green lawns, did not.
For Brecko, now an assistant professor of marketing at the 糖心传媒糖心传媒檚 , the disconnect raised a question that would shape years of research. California was awash in public opinion messaging. Was any of it effective?
糖心传媒淭here was a lot of messaging happening, telling people to reduce their water usage,糖心传媒� she recalls. 糖心传媒淎nd I had these question糖心传媒攊t糖心传媒檚 all marketing, but is it working? What exactly is working and for whom?糖心传媒�
Rather than focusing on the people who had already embraced conservation糖心传媒攖hose willing to let their lawns die or remove them entirely糖心传媒擝recko and Hartmann became interested in the holdouts糖心传媒攖hat is, the households with the highest water consumption. , published in the Journal of Marketing Research, argue that those households should not be shamed or ignored. Instead, they should be targeted.
Harm reduction over abstinence
The study borrows a concept from public health: the idea of harm reduction. Instead of demanding abstinence糖心传媒攏o drugs, no cigarettes, no lawns糖心传媒攖he approach aims to reduce damage among people unlikely to completely quit a harmful action.
In California糖心传媒檚 drought-stricken suburbs, the harm was outdoor irrigation. The tool was a smart irrigation controller, a device that automatically adjusts watering schedules based on weather, soil conditions, and plant needs. The question was whether such a device could significantly reduce water use without undermining more aggressive conservation efforts, like turf removal.
糖心传媒淭here糖心传媒檙e always going to be people who are just not going to do it,糖心传媒� Brecko says, referring to lawn removal. 糖心传媒淏ecause it goes totally against their preferences.糖心传媒�
Working with Redwood City Public Works, the researchers tested whether offering irrigation controllers (at either steep discounts or for free) could change behavior among residents who wanted to keep their lawns green. Crucially, the study took place toward the end of the drought, after years of aggressive messaging and rebates for turf removal had already circulated.
糖心传媒淏y the time we ran our study, people had had the chance to adopt the most effective solution糖心传媒攁t least those people who would do it,糖心传媒� Brecko explains.
That timing mattered. Those most committed to conservation had already removed their turf. That meant the researchers could now focus on everyone else.
Field tests in thirsty times
The team ran two large-scale field experiments in Redwood City. In 2016, roughly 7,000 households were offered discounts on smart irrigation controllers, ranging from 10 percent to 80 percent. Some homeowners were also offered free professional installation.
Adoption was slower than expected.
糖心传媒淚 think people just weren糖心传媒檛 sure,糖心传媒� Brecko says. 糖心传媒淭he device was relatively new, and even the utility company wasn糖心传媒檛 sure what effect it would have on water usage.糖心传媒�
The second experiment, in 2017, scaled up dramatically. About 19,000 households were randomly assigned to receive a free smart irrigation device, available in limited quantities. The process was designed to be as easy as possible: Residents received emails and accessed a dedicated online portal where discounts were applied instantly糖心传媒攏o rebates, no paperwork.
The response was swift. Clearly, price and convenience mattered. Messaging alone did not. 糖心传媒淚ncremental discounts aren糖心传媒檛 really going to do the trick,糖心传媒� Brecko notes. 糖心传媒淲e learned that we needed to overcome some barriers to adoption.糖心传媒�
Who adopted糖心传媒攁nd who saved
The devices appealed most to people who used the most water, with heavy irrigators adopting the device at the highest rates.
糖心传媒淚t allows you to keep the green lawn that you care about.糖心传媒� Brecko says, 糖心传媒淏ut it might allow you to also contribute to that social goal that we care about.糖心传媒�
Once installed, the controllers delivered substantial and lasting savings. Water use dropped by about 26 percent (from a regular irrigation baseline) during shoulder seasons糖心传媒攅arly spring and fall糖心传媒攚hen manual systems often overwater because homeowners forget to adjust them. The reductions persisted for nearly four years, the researchers found.
Among the heaviest irrigators, the water savings were large enough to offset the typical $250 cost of the device in roughly six months. The conserved water alone could cover a household糖心传媒檚 annual indoor needs. But just as important, the study found no evidence that smart controllers undermined more aggressive conservation.
糖心传媒淲e don糖心传媒檛 see any difference in turf removal rates,糖心传媒� Brecko says. 糖心传媒淎nd we see no increases in consumption among non-irrigator households.糖心传媒�
In other words, harm reduction did not 糖心传媒渃annibalize abstinence,糖心传媒� the duo writes.
A middle road for climate behavior
For policymakers, the findings challenge the all-or-nothing approach that often dominates environmental messaging. The most effective solution糖心传媒攖o simply rip out the lawn糖心传媒攚ill never appeal to everyone.
糖心传媒淢y initial inclination is to say everyone should do the thing that糖心传媒檚 most powerful,糖心传媒� Brecko says. 糖心传媒淏ut the thing is, we all have really different preferences.糖心传媒�
While some people care deeply about conservation, others may have competing priorities and care more about their yard糖心传媒檚 aesthetics, their kids糖心传媒� being able to play on grass, or the curb appeal of their home. Stigmatizing the latter group or ignoring their strong preferences, can leave them unnecessarily out of conservation efforts.
糖心传媒淣ot that those high users don糖心传媒檛 care about conservation, it糖心传媒檚 just that they might care about something else more,糖心传媒� says Brecko. 糖心传媒淚f you don糖心传媒檛 engage them, they might do nothing.糖心传媒�
The lesson, she argues, is not to abandon high-impact solutions, but to sequence and supplement them. If you want people who use the most water to conserve, you may have to let them keep what they love, while reducing the shared costs of doing so.
糖心传媒淭hey get the thing that they care about,糖心传媒� Brecko says. 糖心传媒淎nd you, as the conservation-oriented person, get the conservation, too.糖心传媒�
