You should clean your feeder at least once a week or more often if the water gets cloudy.

Per the National Audubon Society, cleaning should be done by rinsing with 1-part white vinegar to 4 parts water. If the feeder is dirty, try adding a few grains of rice to the vinegar solution to help scrub it clean. Follow the vinegar wash by rinsing 3x with clear, warm water before refilling with sugar solution.

If mold develops, you will need to soak the feeder in a 10% bleach solution (1 part bleach to 10 parts water) until the mold is gone. A cotton swab is helpful in removing dirt or mold stuck in feeder ports and a small bottle brush can be handy to scrub crevices. Once the feeder is clean again, rinse it thoroughly, multiple times, removing all traces of bleach.

Over the years, we have found that some of the metal bases on the bird feeders have developed some rust inside. This could be for several reasons other that metal+liquid+air = potential rust. If you keep your feeder clean on a regular basis, that should help the rust from ocurring, but we cannot guarantee that.