Information on To(a)p: An experimental Campaign to Increase the Use of Water Fountains in Mexico City’s Parks

Mexican per capita consumption of bottled water is highest in the world. Part of the reason is that many cities lack potable tap water. Yet, even in Mexican cities where tap water is quality is high, it tends to be underutilized. Could advertising water quality increase tap water consumption? Does it matter who provides the information? To answer these questions, we conducted a randomized controlled trial in eight of Mexico City’s most important enclosed parks, placing large posters with information about tap water quality next to water fountains. We randomly allocated these treatments to parks and days of the week for three consecutive weeks. We found that posters confirming water was free of bacteria increased average water consumption from park water fountains. However, this effect was moderated by three important factors: the park in which the fountain was located, whether the advertisement appeared on weekdays, and the gender of the park user. In addition, conditional on having seen or read the poster, park users consumed more water when the sponsor was a non-governmental institution rather than the public water utility company. Our results suggest that effective information campaigns are feasible and that further research is needed to understand the effect of information on water consumption.