I’ve dealt with this exact frustration, and I totally get it—finding a public trash can with coffee dripping out the bottom is not just gross, it’s a cleaning nightmare. The good news is, you can solve this without becoming the "bin police." Here are a few things that actually work based on real-world scenarios.
First, make it physically inconvenient for liquids to get in. If you’re in charge of a public space, consider replacing or retrofitting bins with a drainage system or a separate liquid collection tray. Some modern bins have a perforated inner bucket that lets liquid drain to a sealed bottom compartment. This means the main trash stays dry, and the liquid is contained. No mess, no smell.
Second, you need clear and friendly signage. Avoid aggressive signs like "No Liquids!" because people ignore or even resent them. Try something more practical and polite: "Please empty your cup in the sink or drain before tossing it here—keeps our park clean!" Or "Coffee cups go in the trash, but please pour out the leftover first." When you frame it as a small favor rather than a rule, people are way more cooperative.
Third, target the source. If this is happening at a workplace or a café, put a separate bucket or a pre-rinse station right next to the waste bin. Have a sign that says "Drain leftover coffee here." This is simple but effective—people need a convenient place to dump the liquid. If it takes extra steps, they won't do it. But if it’s right in front of them, they will.
Finally, consider the bin's design itself. A bin with a smaller opening (a "lid with a hole") makes it harder to pour a big cup of coffee in quickly. It forces people to think—and often, that split-second hesitation is enough for them to decide to pour it out somewhere else first.
Bottom line: Don’t try to change human nature; just design for it. A little planning ahead can save you an awful lot of cleanup.