DWR stands for Durable Water Repellent. The exclusive HydroMax finish applied to the fabric is very durable, even after 5 laundry cycles and sun exposure, it still repels water quite effectively. The duration of the DWR's life depends on many factors, but it can be expected to last anywhere between 3.5 to 5 years before it begins to lose its potency at which point it may be required that one spot treat WeatherMAX with a product like 303