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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. HIGHLIGHTS Being offered a subsidy increased the likelihood that a given household would purchase a latrine by 31% (over ineligible comparison households).; The sales closing rate among eligible households in treatment areas was 38% compared to 6% among ineligible treatment 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.;

Achieving safely managed sanitation (SMS) in rural areas has spurred innovation in toilet designs that provide on-site treatment of fecal sludge (FS), including the development of International Development Enterprise (iDE)’s alternating dual-pit latrine upgrade (ADP). ADPs treat FS by inactivating pathogens using storage treatment with lime; however, ADPs’ reduction in pathogenicity (and thus their associated public health benefit) has not yet been described in real-world pits at scale. We thus enumerate the fecal indicator bacteria Escherichia coli (E. coli) and fecal coliforms in 147 pits after two years of storage treatment with lime and compare detected concentrations to relevant standards. E. coli and fecal coliform concentrations indicated a risk to human health in 31% and 42% of sampled pits, respectively. Regression models described relationships between fecal indicator bacteria concentrations and measured factors (e.g., sludge pH, temperature) but did not reveal any meaningful associations. High rates of pit ineligibility also indicate that many ADPs are not operated as recommended. Results indicate a one-in-three chance that a household emptying their own pit would be exposed to health hazards and call into question the effectiveness of the standard two-year storage treatment in real-world applications. To improve rural SMS, various evidence-based recommendations are made. HIGHLIGHTS Fecal sludge stored in real-world alternating dual-pit latrines after treatment were enumerated for fecal indicator bacteria.; E. coli and fecal coliform concentrations indicated a risk to human health in 31% and 42% of sampled pits, respectively.; Households emptying pits after treatment have a one-in-three chance of being exposed to health hazards.; Many ADPs were not operated as recommended, reducing pathogen inactivation.;