Honestly, the short answer is yes—dome-top bins generally keep rain out better than flat tops, but the difference is usually smaller than the lid shape suggests. A dome sheds water to the sides, so you don’t get a puddle sitting on top and seeping through seams. A flat top can collect water, and if the lid isn’t tight or the seams are tired, that water will find its way in.
That said, a dome top isn’t a rainproof box. Most urban bins have openings, push flaps, or side gaps, and wind-driven rain can still get inside. If the drainage holes are clogged or the bag is torn, water can pool at the bottom either way. A flat-top bin with a good overhang, a tight lid, and working drainage can perform surprisingly well.
So in real streets, the design matters, but so do maintenance and placement. Dome tops are usually the safer choice for exposed sidewalks and rainy cities, especially if the opening is shielded. Flat tops can be fine in sheltered spots or where they’re emptied often. My practical take: dome tops win on average, but don’t expect magic—check the opening, drainage, and how well the lid actually fits.