The 2024 historic floods in Rio Grande do Sul, Brazil, created an unparalleled humanitarian crisis, overwhelming the region’s infrastructure by paralyzing 70 water treatment plants and submerging 265,000 service connections. Facing asset damage and logistical chaos across 168 municipalities, Corsan/Aegea needed immediate, precise decisions to restore basic services for 2.4 million people. The digital breakthrough was leveraging their existing Bentley OpenFlows Water hydraulic models as a tactical-strategic emergency planning tool for the first time. The team rapidly transitioned to action, using the models to simulate complex, time-sensitive scenarios: from strategically locating mobile water treatment units to optimizing the delicate recharge of damaged distribution networks. OpenFlows provided the crucial intelligence needed to calculate replenishment times and test temporary supply loops under extreme uncertainty. This digital response enabled the task force to establish a predictable, organized, and intermittent supply to the entire affected population, ensuring water quality and mitigating the severe public health risks of a complete water shortage. This agile use of advanced digital modeling demonstrates its critical role in climate disaster response and infrastructure resilience.