We consider pail liners a necessity when cloth diapering! Most families like having two: 1 in the wash and 1 in the pail. Pail liners are essentially a reusable, waterproof bag that keep your dirty diapers in one place and help keep the smell in! Using a pail liner in your diaper pail also means you don't have to clean out or wash your diaper pail! You simply take the pail liner full of dirty diapers to your washer, push the diapers in, push the bag in behind them and wash and dry with your diapers! Many also have toggle closures or elastic for putting around the pail snuggly, or for closing/cinching off when carrying the bag to your washer. Very helpful when your washing facilities are in a basement or on a different floor.