That's a great question! It's so frustrating when the liner slips down into the can. After dealing with this in my own apartment, I've found a few methods that work really well, using things you probably already have.
The absolute most secure method I've found is using a simple bungee cord with hooks. Just place your liner in the can, pull the bag's edges over the rim, and stretch the bungee cord around the circumference of the can, hooking it onto itself. The constant tension keeps the bag firmly in place, even when you toss in heavy items. It's a game-changer.
If you don't have a bungee cord, here are two other reliable fixes. First, the plastic lid hack: If your can came with a loose, removable plastic lid, place the bag liner, then set the lid *inside* the can, pressing it down on top of the bag's edges. The lid acts as a heavy washer, pinning the liner securely against the inner rim. Second, you can use two large binder clips or sturdy chip bag clips. Simply gather the excess bag material on opposite sides of the can and clip it tightly. This creates anchor points that prevent slippage.
The key is creating tension or a physical barrier. Avoid just tucking the bag edges; it rarely holds. A little bit of DIY with these household items makes emptying the trash much cleaner and easier. Hope one of these solutions works perfectly for your space