Known as the Cholera Hospital-Based Intervention for 7 days (CHoBI7) mHealth program, health workers provide information, chlorine tablets, a bottle of soapy water, a handwashing station, a safe water vessel, and weekly voice and text messages to reinforce proper hygiene and water treatment behaviors. The program currently costs just $2 per diarrhea episode averted, and is expected to result in future savings as fewer patients will need hospital-based care. The government of Bangladesh is interested in scaling the program, but necessary adaptations must first be rigorously tested to ensure they are effective. With support from Development Innovation Ventures (DIV), Johns Hopkins is conducting a randomized controlled trial to test a scalable version of the CHoBI7 program that examines two significant questions of interest to the government’s plans: “How large are impacts when beneficiaries receive chlorine tablets and soapy water for free, but must purchase and build the other materials themselves?” and “What is the program’s effectiveness in rural areas?”