That's a great and very practical question! The ease of finding replacement bags really depends on a few key factors related to your specific trash can model.
For many standard, commercially available urban or public space trash cans, finding compatible bags is generally straightforward. Major manufacturers like Rubbermaid, Toter, or Simple Human usually have dedicated liner lines, and you can often purchase them directly from their websites, industrial supply companies, or janitorial supply distributors. The model number, typically found on a sticker inside or underneath the bin, is your golden ticket. Searching online with that exact model number plus "replacement bags" or "liners" yields the best results.
However, if your trash can is a custom or very old model, the process can be trickier. In this case, you'll need to become a measurement detective. Accurately measure the can's top dimensions (width/length or diameter), depth, and note the bag's attachment method (drawstring, flap, etc.). With these specs, you can search for "commercial trash bags" by size. Many universal bags are sold by dimensions (e.g., 30" x 38") and gallon capacity.
My top tips? First, identify the manufacturer and model. Second, buy in bulk from supply websites for better value. Third, consider switching to a universal, measured-size bag if proprietary ones are discontinued. While not always instant, with the right information, sourcing replacements is usually a very manageable task.