That's an excellent question! Dealing with a rusty trash can is frustrating and unsightly. Fortunately, you have several great options for materials that stand up to rain without rusting.
The most common and cost-effective choice is Plastic or Polyethylene. Modern plastic bins are incredibly durable, won't rust, and are lightweight. Look for UV-resistant varieties to prevent fading and cracking in the sun. While they can be prone to cracking in extreme cold or if impacted, they are generally a fantastic, low-maintenance option.
For a more heavy-duty and stylish solution, consider Galvanized Steel. This is regular steel coated with a layer of zinc, which acts as a sacrificial barrier against corrosion. It's much stronger than plastic and has a classic, industrial look. Just be aware that if the coating gets deeply scratched, the underlying steel could eventually rust, so handle it with care.
The premium, virtually indestructible option is Stainless Steel. It contains chromium, which forms a passive film that protects against rust. A high-quality stainless steel bin will laugh in the face of rain and look sleek doing it. The main drawback is the higher cost, but it's an investment that will last for decades.
Another excellent material is Resin or Polymer. These are often designed to look like woven wood or stone, blending seamlessly into your patio or garden. They are very durable, resistant to weather, UV rays, and won't rust, chip, or peel.
My final recommendation? For most people, a high-quality plastic or resin bin offers the best balance of weather resistance, affordability, and low maintenance. If you need maximum durability and don't mind the price, stainless steel is unbeatable. Always ensure any can has adequate drainage holes at the bottom to prevent water from pooling and accelerating wear.