You will know it is time to change the bag of the Ubbi diaper pail once you can no longer comfortably place more diapers into it. Filling the bag beyond capacity will make the bag difficult to remove. To prevent too much of the smell from accumulating inside the pail, we recommend changing the bag at least twice a week. Given that you don’t need to buy special refills for the pail, you can afford to change the bag more often.