That's a great question, especially if you're dealing with frequent downpours. I've wondered the same thing when I see bins at the curb. From my experience and research, the answer isn't a simple yes or no—it depends heavily on the bin's design.
Most standard municipal trash and recycling bins provided by cities are designed with some level of water resistance in mind. The lids are typically domed to encourage water runoff, and they often have a lip or a rubber gasket around the rim intended to create a seal when closed. In a light drizzle or brief shower, this design is usually effective at keeping the bulk of water from pouring in.
However, during heavy, wind-driven rain—the kind we both know well—the seal can be compromised. Wind can lift the lid slightly, or water can be forced through the small gaps around the hinge or between the lid and the body. Over time, seals can wear out, lids can crack, or bins can become slightly misshapen, all of which reduce their effectiveness. The result is often a bin with several inches of water at the bottom, leading to heavier, messier trash and potential issues with pests and odor.
If you're concerned, here are a few things you can do: Make sure the lid is always fully closed and that no trash is preventing a tight seal. Store the bin in a sheltered location if possible, even just against a wall. Some residents add a brick or a weight on top of the lid during major storms to prevent it from lifting. If your bin is consistently collecting water and is damaged, contacting your local public works department to request a repair or replacement is a good step.
So, while they are engineered to shed water, most urban bins are not completely waterproof. They're more accurately described as "weather-resistant," performing well in average conditions but potentially struggling in the exact kind of severe, persistent rain we often get.