We’ve all heard the edicts:

Take shorter showers. Wash full loads of laundry. Swap out that water-hogging grass for something native.

Those are simple strategies to cut residential water use by 25 percent, as Gov. Jerry Brown mandated this month in an emergency response to California’s extreme drought.

Too bad it’s not going to be that easy.

As much as we may be motivated to change ingrained actions with a precious resource that’s becoming even more precious with each sunny day, psychologists say change is hard.

And that’s especially true when the change you’re seeking involves using less of something that’s essential, fairly cheap and flows (literally) down a drain.

“Providing … facts is generally not sufficient to change people’s behavior,” said Wesley Schultz, a professor at California State University, San Marcos, who specializes in the psychology of environmental behavior.

“We need to give people a sense that their actions can make a difference, and help them to translate that motivation into behaviors that matter.”

Orange County already has reduced its water use by 25 percent. It just took 25 years for that to happen. From 1990 and 2014, county residents reduced their per capita water use to where it is today: 140 gallons per person per day, according to the Metropolitan Water District of Orange County.

But in year four of our current drought, we don’t have the luxury of 2 1/2 decades to cut another 25 percent, a figure that translates to 35 gallons a day.

Finding, storing or purifying more water – whether it’s with dams, aqueducts, aquifers or desalination plants – takes years to achieve, costs billions of dollars and is fraught with politics.

Reducing demand is the quickest solution.

“Most consumers dramatically underestimate how much water they use. Therefore, they misunderstand the best ways to be efficient,” said Robin Gilthorpe, chief executive at WaterSmart, a San Francisco-based software company that has partnered with a handful of water agencies in Orange County, including those serving Irvine, Huntington Beach, Newport Beach and Santa Margarita.

Using data from residential water meters, and pairing that data with typical water consumption based on climate, lot size, number of household residents and amenities, such as swimming pools, WaterSmart can tell homeowners how their water use compares with similar households. It also offers targeted and relevant suggestions on how they might improve.

“If we know you live in a house built before 1994, and haven’t done a permit or major retrofit, there is an 85 percent chance that you would be a good candidate for low-flow toilets and (low-flow) showerheads,” Gilthorpe said.

That year, 1994, is also when the U.S. Environmental Protection Agency started to require residential toilets to flush with no more than 1.6 gallons, down from 3 gallons or more. Today, some low-flush toilets can do the deed with less than 1 gallon.

But using a low-flow toilet is just one water-cutting suggestion WaterSmart provides customers. The system also provides motivation, in the form of detailed (and easy-to-understand) details on your home’s water use versus others in your neighborhood.

That information can gradually nudge water hogs back in line.

“Social norms impact all of us,” Gilthorpe said.

“If we tell you that other people who live in a house like you with similar occupancy in a similar climate are using half as much water as you are, it’s interesting … Over time, people’s behavior tends toward the norm,” he said.

Newport Beach was one of the first Orange County cities to adopt the WaterSmart system.

Launched in January 2013 as a 2,500-home pilot program to save water and send less pollution into the ocean, the WaterSmart system managed to cut water use by an average of about 3 percent per home during the next 18 months. The program is being expanded and is expected to go citywide, to 23,000 residences, by the end of this year.

“It’s really behavior change we’re trying to foster, not just an intermittent, we’re-in-a-drought mentality,” said Shane Burckle, a conservation specialist for Newport Beach.

Burckle’s department also offers residents rebates for turf removal, weather-based irrigation controllers, rain barrels, low-flush toilets and other water-saving systems.

One of the most effective of those systems is a smart water meter, which can monitor water use down to the hour, another valuable feedback tool in sparking behavioral change.

Kenneth Small, an environmental economist and professor emeritus at UC Irvine, cited an Arizona study that compared water use in suburban homes that had meters that closely tracked consumption versus homes that didn’t.

“The ones that had the meters were much more water saving,” Small said. “They tended to have desert landscape and drip irrigation, whereas the (homes) that had no meter looked like Irvine.”

As valuable as feedback is for homeowners to understand their water use and make changes, basic economics are also effective.

Water agencies’ use of tiered pricing, which charges homeowners higher rates when they use more water, is another way to change behavior, Small said.

“Generally, people will cut back on any particular good the more expensive it gets,” said Small, who added that water savings can be prodded with a combination of incentives (rebates and other rewards for using less water) and penalties (tiered pricing and fines).

“For voluntary measures, carrots work better. If you convince people that it’s in everybody’s best interest, maybe they’ll monitor themselves better and try to do what they think is the right thing.”

But, Small added, incentives can have a downside.

“People will take an environmental action in one area, and … feel so good that they’ll splurge on something which might undermine the same thing, or contribute to another environmental problem.”

Punitive measures can have a downside, too, he said.

“If people are forced to limit their irrigation by some kind of restriction, and they resent it, they might comply because they don’t want to get fined,” Small said.

“But they might take (the reduction) back by taking a longer shower, or doing something else where their behavior is not being monitored.”

Contact the writer: scarpenter@ocregister.com Twitter: @OCRegCarpenter