That's a great and very practical question! As someone who's worked with municipal services, I can tell you that securing public bins is a constant battle against theft, vandalism, and just general misuse. There isn't one single "most secure" method, but rather a layered approach that combines the right hardware, smart placement, and sometimes a bit of psychology.
First, let's talk hardware. The chain itself should be a heavy-duty, welded steel chain with links at least 10mm thick. Forget cheap hardware store options. Pair it with a high-quality, shrouded padlock (like a disc lock or a shrouded shackle lock) that protects the locking mechanism from bolt cutters and tampering. The anchor point is critical—it must be bolted into solid concrete or masonry using concrete anchor sleeves and security bolts, not just screwed into a wooden post.
The chaining technique matters too. Don't just loop it loosely. Thread the chain through both the bin's built-in handles or frame and the anchor point, keeping it taut to minimize slack that gives leverage to tools. For wheeled bins, always secure the wheel frame, not just the body.
Beyond the chain, consider the environment. Placing the bin in a well-lit, high-visibility area is a natural deterrent. If possible, use a fixed metal post or a dedicated bin corral as your anchor point, which is more robust than a signpost. For very high-risk areas, you might look into specialized locking bars that completely immobilize the lid and body, or even bins that are permanently embedded in concrete foundations.
Finally, remember that maintenance is part of security. A regularly emptied and cleaned bin is less likely to be a target for misuse. The goal is to make stealing or vandalizing the bin more trouble than it's worth, ensuring it stays where the community needs it.