That's an excellent and practical question! It gets to the heart of why some public bins seem indestructible while others are constantly knocked over. The short answer is that there's no single universal "depth," but rather a combination of design principles that work together to prevent tipping.
First, it's crucial to understand that "depth" alone—meaning how far the bin extends into the ground—is rarely the primary solution. For permanent, heavy-duty public bins, stability comes from a foundation and anchoring system. A common best practice is to set the bin's base in a concrete footing. The bin's steel post or base plate is embedded into the wet concrete, which then cures, locking it firmly in place. The "depth" here is more about the concrete mass's volume and spread below grade (often 18-24 inches/45-60 cm deep and wider than the base) than the bin's own length.
For surface-mounted bins that aren't permanently cemented, counterweight and a low center of gravity are the keys. A well-designed bin will have a heavy, wide base—sometimes filled with sand or ballast—that makes the bottom significantly heavier than the top. This design means the bin must be tilted past a high tipping point before it falls. The "depth" or height of the bin itself is a factor here; a taller, narrower bin is inherently less stable than a shorter, wider one of the same volume. The base should be at least 2/3 the width of the bin's height for good passive stability.
Other critical factors include:
* Anchor Points: Many bins have flanges for bolting directly to a concrete pad or sidewalk.
* Wind Load & Vandalism: Design must account for strong winds and occasional pushing or leaning. A secure lid also prevents the bin from becoming top-heavy when full of lightweight materials.
* Placement: Positioning a bin against a wall or within a sheltered alcove physically blocks it from tipping in at least one direction.
In summary, while a deep, secure foundation is ideal for permanent installations, the industry standard focuses on a wide, heavy base and a low center of gravity more than a specific burial depth. A properly engineered 50-gallon public bin with a weighted base and anchor bolts will be far more stable than a deeply buried but lightweight and narrow post. The goal is to make the force required to tip it far exceed what casual contact or weather would typically apply.