Poor drainage is a major cause of premature road failure. When drainage is inadequate, water can weaken pavement materials in several ways. It reduces the strength of unbound materials in the pavement layers and subgrade. Fluctuating moisture in expansive subgrade soils can cause differential swelling and cracking. Water can also cause mud pumping in flexible pavements and stripping of asphalt. Several case studies from India are described where roads exhibited accelerated deterioration due to issues like blocked drains allowing water to pool on the surface, high water tables causing capillary rise, and flooding from adjacent land or structures overwhelming drainage capacity. Proper drainage is critical for maintaining the bearing capacity and extending the lifespan of roadways.