That's a great question! It might seem puzzling at first—how can a bin without a bottom, sitting right on concrete, handle drainage without creating a mess? The secret isn't in the bin itself being a drain, but in the integrated system it's part of.
Typically, these "bottomless" bins are installed over a pre-built drainage inlet or grate embedded directly into the concrete pavement. The concrete surface is sloped (a process called grading) to channel rainwater and any bin liquids toward this specific point. The bin acts as a cover and a collection point for solid waste, while liquids simply pass through its open bottom, down through the grate, and into the underground stormwater drainage network.
This design is intentional and smart. It prevents the bin from becoming a stagnant, waterlogged container that breeds bacteria and mosquitoes. It also helps rinse away residues, reducing odor. The key is that the bin and the concrete are not separate; they are components of a single engineered solution. Maintenance crews regularly remove the bin liner with solid trash, while the drainage below handles fluids independently, keeping the area cleaner and more hygienic. So, it's not magic—it's practical urban infrastructure working as designed.