I have one upstairs and one downstairs and we empty every time we vacuum. When I just bought the first one, I had just vacuumed the family room carpet with the old Sanitaire (Hoover) and believed the room was pretty clean. Ran the Dyson Animal DC14 over the same carpeted surfact and picked up 1/2 canister full. I didn't know whether to be impressed or depressed so I emptied the canister and ran it all over the room some more and couldn't get another 1/4 inch of dirt on the second run. Yeah, I was sold and that's the vacuum I use everywhere now.