That's a common and frustrating problem! The bottom of an outdoor trash bin takes a beating from moisture, weight, and constant movement. Here are some natural, practical tips I've found work well.
First, consider a liner. A simple, heavy-duty plastic bag (like a contractor bag) lining the entire interior creates a moisture barrier. For even more protection, place a cut piece of plywood or a plastic drip tray at the very bottom before the bag. This distributes the weight and prevents sharp objects from poking through.
Elevation is key. Never let your bin sit flat on wet ground or concrete. Use bricks, pavers, or specially made plastic stands to lift it an inch or two. This allows airflow to dry the bottom and prevents rust or rot from constant dampness.
Be mindful of what you toss. Drain liquids from containers before disposal. Try to avoid throwing away extremely heavy, concentrated items. Distributing weight evenly helps.
Give it a simple cleaning routine. Every few months, empty and rinse the bin. Let it dry completely in the sun before putting a new bag in. This prevents grime and moisture from constantly eating away at the plastic.
Finally, if your bin is already old, a repair might help. For plastic bins, clean and dry the area, then apply a waterproof epoxy or a heavy-duty patch kit designed for plastic. It can buy you more time.
A little prevention goes a long way. Using a liner and keeping the bin elevated are the two most effective steps you can take to dramatically extend the life of your trash can's bottom.