It's recommended that the dustbins of Roomba 400 - 900 series vacuum cleaners are emptied after each use. Essentially when the Roomba runs out of battery, empty the dustbin. How often you run your Roomba vacuum is up to you. However, it also depends on other factors, such as how many pets or children you have. Or how much dust generally collects in your home. So, some circumstances may require more frequent dustbin emptying.