That's a great question! Dealing with a floppy or slipping liner bag in a big outdoor bin is a common frustration. The best way to mount it securely depends on your can's design, but here are the most effective and simple methods.
The classic and highly effective solution is to use a bungee cord or heavy-duty elastic loop. Simply place your bag in the can, pull its edges over the rim, and then stretch the bungee cord around the circumference over the bag's material. This creates downward pressure that holds the bag firmly against the inner walls, preventing it from falling in. It's quick, adjustable, and works on almost any can.
For cans with a rolled or lipped rim, large binder clips or sturdy spring clamps are a fantastic low-profile option. Clip them at several points around the rim, pinching the bag material between the clip and the rim. This method is very secure and keeps the bag's opening fully accessible.
Another popular hack is to use strong adhesive hooks (the kind meant for outdoor or heavy-duty use). Stick two or three hooks on the *outside* of the can, just below the rim. After placing your bag, you can loop the bag's drawstring or the excess plastic over the rim and hook it onto these hooks. This is particularly good for bags with drawstrings.
If you want a permanent, built-in solution, consider installing pop rivets or grommets. You can add a few small grommets around the top inner wall of the plastic can and use carabiners or zip ties to attach the bag loops. This is more work upfront but provides a very reliable anchor point.
A final tip: always ensure the bag is fully unfolded and spread out before securing it. A bunched-up bag is more likely to slip. Combining a well-spread bag with one of the mounting techniques above will solve 99% of your bag slippage problems, keeping your outdoor area cleaner and making trash changes much easier.