That's an excellent and very practical question. As a restaurant owner in an urban area, I've dealt with this firsthand. The "best" locking mechanism isn't one-size-fits-all; it depends on your specific bin type, location, and threats like scavenging, illegal dumping, or pest access. Let's break down the top options.
For standard rear-alley dumpsters or enclosed waste corrals, a heavy-duty, shrouded steel padlock with a hardened steel hasp is the classic, robust choice. Look for weather-resistant models (e.g., marine-grade) to withstand the elements. The shroud protects the shackle from bolt cutters. This is ideal for deterring casual tampering and locking gates.
For individual wheeled bins, integrated cam locks or latch locks are often more effective. These are built directly into the bin's lid, providing a cleaner, more tamper-resistant solution than an external padlock. They require a specialized key, preventing casual rummaging and helping to comply with local ordinances regarding secured lids for pest control.
In high-theft areas where waste like used cooking oil is targeted, consider smart locks or proprietary locking systems. These can include barrel locks unique to your waste hauler or even Bluetooth-enabled locks that log access times. They offer the highest level of control and audit trails.
My final piece of advice? Always coordinate with your waste management company first. Many have specific requirements or provide their own locking systems as part of their service. Combining a physical lock with strategic placement—well-lit, in sight of cameras if possible—creates the most secure setup. Start with a heavy-duty hasp and padlock for simplicity and cost-effectiveness, and upgrade to integrated systems if you need a more seamless or stringent solution.