That's an excellent and very practical question! Living in a rainy city definitely makes you notice these everyday details. From my observations and research, the answer is generally yes, most modern urban trash bins are designed to be waterproof or at least highly water-resistant, but with some important nuances.
You'll notice that public litter bins and larger communal waste containers typically have lids, often with a swinging or hinged design. These lids are the first line of defense. Their primary purpose is to contain odors and deter pests, but they also do a great job of preventing rainwater from directly flooding the bin. Many are weighted or designed to fall closed automatically.
For the bins themselves, the materials matter a lot. Most are made from durable plastics like polyethylene or metals like galvanized steel. These materials themselves are impervious to water and won't rust or degrade quickly from moisture. The key is in the construction. Well-designed bins will have sealed seams or be molded as one piece to prevent leaks. You might also see small drainage holes at the very bottom of some bins. This seems counterintuitive, but it's intentional—it allows for any minor condensation or incidental water (from a melting ice pop, for example) to drain out, preventing a smelly, stagnant soup from forming at the bottom.
However, in extremely heavy downpours or if a lid is broken or left open, water *can* get in. This is why municipal cleaning crews often have to service bins—to empty accumulated water along with the waste. The real concern for city planners isn't just a bit of rainwater inside, but whether the bin's structure can withstand constant moisture without corroding, and if the internal waste doesn't become overly saturated and too heavy to handle.
So, while your city's bins are likely built to weather the storm, so to speak, their effectiveness depends on good design, intact lids, and proper maintenance. It's a small but crucial part of keeping a rainy city clean and functional!