..A new approach places chlorine dispensers at communal water sources. Using larger, community-level containers substantially reduces packaging costs, making it easier for governments or donors to provide the chlorine for free. The dispensers deliver the right quantity for the standard water-collection container, so the dispenser is convenient to use. The dispenser itself provides a visual reminder of the need to treat water, and combining the steps of water collection and treatment builds good habits. The public placement of the dispenser is designed to facilitate peer pressure and social-norm formation around chlorine use.

Whereas less than 10 percent of people treated their water under the social-marketing approach, most people did so in communities with a chlorine dispenser. Moreover, in contrast to cases in which prevention campaigns generate an initial burst of enthusiasm that wanes over time, most people continued to treat their water two and a half years after the evaluation, perhaps because of the peer-pressure mechanism that was built into the design.