Marine canvas is not waterproof; it is water repellent. This means that during the finishing process a water repellent finish is applied to the fabric. The effectiveness of the water repellent finish diminishes with normal usage. Marine canvas requires constant cleaning in order to prevent dirt from being embedded in the fabric. Manufacturers of marine canvas recommend it be cleaned monthly with clear water, and thoroughly cleaned every couple of years. Canvas requires re-application of a water repellent treatment such as 303 High Tech Fabric Guard after every cleaning in order to maintain water repellence. Improper care of canvas will significantly reduce its life expectancy. Most marine canvas has a 3 to 5 years warranty.