Flash floods are common in the town of Kokrajhar in north-eastern Indian state of Assam. Many areas in the town of Kokrajhar are submerged in water almost every year due to floods during rainy season. These floods cause heavy damage to roads, agricultural production and halt the progress of major infrastructural development projects. Hence, prevention of floods has become an important concern in the town of Kokrajhar. This study investigated the causes of floods and offered a solution for their elimination. The investigation showed that inadequate and inefficient network of storm drains was the reason for the flash floods. A new drainage network for the town of Kokrajhar has resulted from studying the shortcomings of the existing network of storm drains. The new network is designed in accordance with the recommendations stated in the “Manual on storm water drainage systems” prepared by the Central Public Health and Environmental Engineering Organization in 2019.