Testing Low-Cost Information to Drive Household Water Conservation
Since 2022, the Energy and Environment Lab has partnered with the Westminster, Colorado, to generate rigorous evidence to support the city’s water conservation efforts. We have designed and launched three randomized control trials to evaluate the impact of information provision on household water consumption and price-related misperceptions.
As part of the first experiment, the city sent email and postcard appeals to ~11,000 households encouraging them to sign up for the city’s information portal, which lets residents see hour-by-hour smart meter water use data. The information provided in the appeal included leak alerts, easier bill payment, or water use tracking. We found that the campaign doubled customer enrollment in the portal, which increased from ~1 percent to ~2 percent of households enrolling. Leak warnings were twice as effective well as either alternative, and emails outperformed postcards. However, no significant reduction in water consumption accompanied this increase in enrollment.
The second experiment focused on ~7,000 households identified as engaging in inefficient irrigation behavior: irrigating more frequently than recommended (frequency) and irrigating during high-evaporation daytime hours (timing). Treatment households received an email notifications informing them that the utility has observed inefficient irrigation patterns and offered specific, actionable recommendations to improve irrigation efficiency. We found that frequency notices decreased average household monthly water use by ~960 gallons, and timing notices reduced mid-day watering events by approximately 8 percent.
Results: A single email about how often to irrigate decreased average household monthly water use by 960 gallons, at no cost to the utility.
For the third experiment, we study whether water pricing can drive conservation. We measure the extent of household misperceptions about marginal prices and water consumption, and whether informational interventions intended to alleviate these misperceptions can drive water conservation. First, we implemented a baseline survey to measure households’ understanding of their water use and details of the city’s water pricing schedule. Among the ~2000 customers who answered the survey, baseline misperceptions were substantial – most customers were unable to correctly identify marginal prices, despite the price of water nearly doubling above particular thresholds. Furthermore, households underestimated their average monthly water use by ~4,200 gallons.
Following the baseline survey, customers were randomly assigned to control group or one of three treatment arms: scheduled consumption notifications, scheduled consumption notifications with an explanation of the marginal pricing schedule, and real-time alerts when cumulative use exceeded pricing thresholds. All notifications proved highly effective. Our midline survey showed that the intervention decreased misperceptions by a factor of 2, and households reduced their average daily water consumption by ~13.5 gallons. Our team is currently quantifying the consumer surplus gained by reduced misperceptions, and testing whether corrected beliefs and lower consumption persist once notifications stop.