<p>Climate change has intensified the frequency and severity of water-related disasters (WRDs), including floods and cyclones, thereby increasing the burden of water-related infectious diseases (WRIDs) among vulnerable populations. Older adults, who experience age-related frailty and a high burden of chronic conditions, may face disproportionate risks; however, empirical evidence linking WRD exposure to WRIDs among older adults in India remains limited. The present study addresses this gap using individual-level data from the Longitudinal Ageing Study in India (LASI) Wave 1. Descriptive and inferential statistical analyses were employed to examine the association between WRD exposure and WRID prevalence. Overall, 21.3% of older adults reported at least one WRID, with a substantially higher prevalence among individuals exposed to WRDs (28.9%). Exposure to WRDs was significantly associated with higher odds of WRIDs (adjusted odds ratio [AOR]: 1.28; 95% CI: 1.22–1.35). Compared with individuals from arid regions (reference category), those residing in coastal and island regions exhibited higher odds of WRIDs (AOR: 6.68; 95% CI: 3.42–13.07). Unhealthy practices, such as the use of untreated drinking water, were also associated with higher odds of WRIDs (AOR: 1.12; 95% CI: 1.07–1.17). Chronic illnesses and limitations in activities of daily living further increased vulnerability, whereas urban residence was associated with lower odds of WRIDs compared with rural residence (AOR: 0.66; 95% CI: 0.63–0.69). These findings highlight the heightened vulnerability of older adults to WRIDs following WRD exposure and underscore the need for climate-resilient water, sanitation, and hygiene systems and disaster-sensitive geriatric health strategies to accelerate progress toward Sustainable Development Goal 3 (SDG 3).</p>