That's a great question, and one that's crucial for keeping a small plaza clean and welcoming. There isn't a single perfect size, as it depends on a few key factors. For a typical small urban plaza, I'd generally suggest starting with a medium-capacity bin, around 30 to 50 gallons (approximately 110 to 190 liters).
The main thing to consider is foot traffic. A quiet, neighborhood plaza might do well with a few 30-gallon bins. However, a plaza near cafes or transit will need larger 50-gallon bins or simply more bins to handle the volume. You want to avoid overflow, which is the biggest culprit for litter.
Placement is just as important as size. Strategically put bins at natural gathering points—near seating areas, entrances, or food vendors. It's better to have several adequately sized bins in the right spots than one or two enormous ones tucked away.
Also, think about maintenance. How often can your team empty them? A larger bin might need less frequent emptying, but it will be heavier to handle. A smaller bin that's emptied daily is often cleaner than a massive, overfull one.
Finally, consider the bin's design and opening. A good lid with a sensible aperture (not too small) helps contain odors and prevents large bags of trash from being stuffed inside. For a plaza, durability and aesthetics matter too—it should withstand public use and look decent in the space.
So, my core advice: assess your daily traffic, plan for multiple medium-capacity bins in high-activity zones, and commit to a regular emptying schedule. This balanced approach usually works best for small urban plazas.