Natural disasters often cause serious disruptions to clean water and sanitation systems, which directly impacts the increased risk of environmentally-related diseases in affected communities. Emergency sanitation is a key component of post-disaster health responses, but its availability and quality vary widely across evacuation sites. This study aims to analyze the relationship between emergency sanitation access and the incidence of environmentally-related diseases in communities living in post-disaster evacuation sites. The study used an observational analytical design with a cross-sectional approach and involved 210 adult respondents in evacuation sites in disaster-prone areas in Indonesia. Data were collected through structured interviews and observations of ion conditions, then analyzed using the Chi-Square test and logistic regression. The results showed that 60.0% of respondents lived in environments with inadequate emergency sanitation access and 41.0% of households reported incidences of environmentally-related diseases. There was a significant relationship between emergency sanitation access and disease incidence (p = 0.001), with respondents with inadequate sanitation having a higher risk of disease. Multivariate analysis showed that inadequate emergency sanitation was the dominant factor (OR = 2.98; 95% CI: 1.63–5.44), followed by overcrowding and hygiene practices. This study concluded that providing adequate and timely emergency sanitation is a priority intervention to reduce the burden of disease and improve community health resilience in post-disaster situations.