<p>Documenting Indigenous Technical Ecological Knowledge (ITEK) is a necessary central idea for future research support. It is significant for providing sustainable solutions to contemporary challenges such as climate change, water scarcity, and natural disasters. This study documents the Kanmoi tank system for freshwater conservation in the dryland regions of Tamil Nadu in India. Kanmoi Tanks in Dryland (KTD) is a sustainable and centuries-old approach that interconnects tanks via water channels to efficiently harvest, store, and distribute water for domestic use across plain and low-rainfall landscapes. So, using an autoethnographic approach, the study documents the traditional ecological knowledge, practices, and lived experiences of indigenous communities. The findings reveal that the KTD is mainly limited to the districts of Sivagangai, Pudukkottai and Ramanathapuram in Tamil Nadu, which ensures water security and supports livelihoods. The study further identifies conceptual similarities between Tamil Nadu’s large-scale depth KTD model and North Africa’s chained surface-level half-moon water-harvesting model, which primarily serve to combat desertification. So, KTD provides additional strength to the North African model for long-term water storage. As a result, the KTD model contributes to achieving Sustainable Development Goals (SDGs) 6 on clean water and 13 on climate action. It is the evidence-based suggestions that indicate suitability for dryland regions and support sustainable structures for water resilience.</p>