The average home will gather about 40 pounds of dirt a year. That means, if you are not removing that amount, it’s still in there somewhere. The typical central canister will hold approximately 50 pounds of dirt and debris. So you only have to empty the dirt bucket once or twice a year. Obviously, if you have several large dogs that shed or a dozen cats, you need to empty the machine will be more frequent. Same is true if you live on a farm or out in the forest or have a large family, more dirt will be coming into the home.