In a coastal city, I’d normally expect a metal urban trash bin to last around 8–12 years, assuming it’s a standard powder-coated or galvanized steel model and gets reasonable maintenance. If it’s cheaply painted mild steel and sits right on the seafront, 5–7 years is more realistic; once rust starts at the base or around the lid hinge, replacement often comes sooner than people expect.
Stainless steel bins, especially 316-grade, can stretch to 15–25 years, but even they need rinsing and inspection because salt film and humid air wear down fittings and welds. The biggest factors are salt spray, wind-driven moisture, standing water in the base, coating quality, and how often the bin is cleaned and repaired. A coastal bin that’s rinsed regularly, has drainage holes, and gets touch-up paint on chips can easily outlast one that’s ignored.
So the short answer: about a decade is typical for a metal coastal trash bin, with a realistic range of 8–12 years for standard steel and 15–25 years for good stainless steel. If maintenance is poor, cut those numbers down.