Access to safe sanitation is a basic requirement for human well-being and is critical for protecting public health and preventing environmental contamination at the community level. The increasing global risk of climate-related disasters exacerbates the likelihood of traditional sanitation solutions failing and exposing communities to harmful pathogens. This risk is ubiquitous in Cambodia's flood-prone Tonle Sap Lake region, which has some of the lowest rates of sanitation coverage in the country. This study sought to design and test a targeted mechanism in the region to deliver sanitation subsidies to households in a vulnerable position due to climate and socioeconomic characteristics. Subsidy eligibility was evaluated using the poverty probability index for Cambodia, with thresholds set according to households' individual and community-level climate vulnerability. In a randomized controlled trial, offering subsidies increased the likelihood of successful sales conversions for climate-resilient latrine products among targeted households by 32 percentage points, indicating effectiveness for increasing market-based sanitation uptake. The research did not find evidence of widespread or sustained market distortion due to the subsidy program.

  • Being offered a subsidy increased the likelihood that a given household would purchase a latrine by 31%.

  • The sales closing rate among eligible households in treatment areas was 38% compared to 6% among ineligible households.

  • When offered a subsidy, households who were climate vulnerable were most likely to purchase a latrine.

  • No evidence of significant market distortion due to the subsidy was identified.

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