Diaper Pail Liners (for dry pails) Optional technically, but nice

A diaper Pail Liner is basically a garbage bag for your diaper pail.  Most diaper pail liners are made with PUL. They have an elastic band around the top and some even have a portion in the bottom for putting Tee-Tree oil or some other smell-reducing substance. While these work beautifully, and are pretty, they’re not necessarily essential

A lot of people simply use a pillow case! Seriously. Just put the pillow case in the pail, then every couple of washes, toss it in with the diapers so it can be cleaned. But I’d suggest marking it as the diaper-pillow case so it doesn’t accidentally get used as a linen. You can, of course, add elastic to the outside of the case if you wish to make it stick to the diaper pail better, but that’s up to you!
The only thing I’d really recommend is NOT using just regular trash bags. They are plastic and will have to be tossed after every use to prevent bad smells from staying in your diapers. Using a pail-liner or pillow case is much cheaper than having to replace a diaper-pail trash bag every other day. Plus its better for the environment and everyone loves that