That's a great and practical question! Keeping public trash cans secure in cities is a common challenge, aimed at preventing overflow, animal scavenging, and illegal dumping. The "most secure" method often depends on the specific bin type and location, but here are the top, most effective approaches.
For standard commercial bins with lift-up lids, a heavy-duty padlock and hasp system is highly effective. Install a sturdy steel hasp on the bin and its lid, and use a weather-resistant, shrouded padlock. For bins that need to be opened frequently by crews, a combination lock or keyed-alike locks streamline access.
In high-vandalism areas, consider tamper-proof locks like internal barrel bolts or slam locks that engage automatically when the lid closes. These require a special key or tool to open, deterring casual tampering.
A simple, low-cost DIY solution is using a bungee cord or heavy-duty security strap with a carabiner. Loop it through the bin's handles and secure it tightly. While not impervious, it effectively deters animals and casual littering.
For wheeled bins that must be emptied into trucks, a security chain threaded through the lid and bin body, fastened with a robust lock, works well. Ensure the chain is tight to prevent the lid from being lifted.
The core principle is to make accessing the bin more difficult than simply walking to the next unsecured one. The goal isn't always absolute fortress-like security, but rather deterrence—effectively preventing pests, controlling waste volume, and discouraging improper use, thereby keeping our public spaces cleaner and more hygienic for everyone.