That's an excellent and very practical question. As someone who's managed public spaces, I've had to evaluate this exact choice many times. The short answer is: both have their place, but their durability profiles are fundamentally different, addressing distinct challenges.
Let's break it down. Modern heavy-duty plastic bins, typically made from polyethylene, excel in impact resistance. They won't dent like metal if hit by a vehicle or a heavy object. More crucially, they are completely immune to rust and corrosion. This makes them champions in coastal areas with salty air or in places where de-icing salts are used in winter. They're also non-conductive and don't get extremely hot or cold to the touch. However, their main weakness is long-term exposure to intense UV sunlight, which can cause fading and, over many years, make the plastic brittle. High-quality resins with UV inhibitors significantly mitigate this.
Traditional metal bins, often galvanized steel or aluminum, are structurally rigid and very resistant to vandalism like scratching. They have superior weight, which can be an advantage in windy spots. Galvanized steel is quite rust-resistant, but if the coating is scratched or compromised, corrosion can set in. They are also prone to denting, and their painted finishes can chip. In terms of pure material strength under load, metal often has an edge.
So, which is more *durable*? It depends on your primary threat. For chemical corrosion and impact, high-density plastic bins frequently outperform. For structural rigidity and resistance to extreme heat or targeted abuse, metal may hold up better. In my experience, well-made plastic bins often offer a longer, maintenance-free lifespan in general urban settings—commonly lasting 7-15 years without major issues—while metal bins may require more frequent touch-ups or repairs but can have a very long life if maintained.
The smart choice isn't just about material; it's about matching the bin to its specific environment and use case.