That's a great question, and a common headache for anyone dealing with curious raccoons, stray dogs, or windy days. The "most secure" method really depends on your specific problem—whether it's clever wildlife, strong winds, or just keeping the lid firmly closed.
For a robust, all-around solution, a commercial trash can lock or latch kit is your best bet. These are often heavy-duty straps, clips, or bars made from durable plastic or metal that physically clamp the lid to the bin's body. They're designed for this purpose, are relatively easy to install, and offer a strong deterrent. You can find them at hardware stores or online.
If you need a quick, low-cost fix, heavy-duty bungee cords with hooks are surprisingly effective. Criss-cross one or two cords over the lid, hooking them onto the bin's handles or rim. The tension keeps the lid tightly sealed. Just ensure the cords are UV-resistant for outdoor use.
For determined wildlife like raccoons, consider a locking mechanism they can't easily manipulate. A simple carabiner clipped through the lid and bin handle works well. Even better, drill a small hole through the lid's handle and the bin's rim and secure it with a lockable latch or a padlock (if your bin has handles that align). This is a very secure, though slightly more involved, DIY method.
Remember, the goal is to eliminate any gap or leverage point. Always choose bins with tight-fitting, hinged lids when possible. Whichever method you pick, consistency is key—always re-lock it after dumping the trash. A securely locked bin keeps pests out, prevents messy spills, and helps maintain a cleaner, more pleasant outdoor space for everyone.