The longevity of house paint stored in a can depends on whether it is water-based or oil-based and how well it is stored. Unopened cans of water-based or latex paint can last up to 10 years if kept in a cool, dry place with a consistent temperature. Once opened, latex paint can last for about 2-3 years if sealed tightly and stored properly. Oil-based paints, on the other hand, have a slightly longer shelf life. Unopened cans can last up to 15 years, while opened cans, if sealed properly and stored in a cool, dry environment, can last about 3-4 years. To ensure the paint remains usable, always keep the lid tightly sealed and store the cans away from extreme temperatures and moisture. Before using old paint, check for any signs of spoilage, such as a foul odor or significant separation that cannot be stirred back together.