That's an excellent question that many people wonder about when using public trash cans in cities. Generally speaking, most municipal trash cans in urban areas do come with liners already installed. Cities typically have maintenance crews who regularly replace these liners as part of their sanitation protocols. However, this isn't universal - some smaller municipalities or specific locations might not provide liners consistently.
For public trash cans in parks, sidewalks, and other common areas, you typically don't need to bring your own liners. The city's sanitation department handles this responsibility. The liners help maintenance staff efficiently empty the bins while keeping them cleaner.
If you're asking about your personal home trash cans in an urban setting, that's different - those would require you to purchase liners separately. But for public receptacles, the system is designed to be user-friendly without requiring additional supplies from citizens.
It's worth noting that even when liners are present, it's always considerate to ensure your waste is properly contained before tossing it. If you notice a public trash can missing its liner or overflowing, it's best to contact your local sanitation department rather than attempting to address it yourself.