Rust affects metal objects, but it can also stain plastic surfaces where they come into contact with metal; for example a leaky tap mounted on an acrylic basin. If you have attempted to remove the rust spots and stains with regular household cleaners, it's likely some of the rust peeled off. However, completely removing rust stains from your plastic surfaces or containers requires a substance that can actually break up the rust. Soap doesn't dissolve rust stains, but white vinegar will.
Place the plastic on a flat surface outside or in a well-ventilated area. If you can't move the plastic object, open a window to ensure the room is ventilated.
Pour 500 ml (2 cups) of white vinegar into a bucket. Wear rubber gloves to stop the vinegar getting on your hands.
Place a clean rag or sponge in the bucket. Let the rag or sponge stay in the vinegar for about 30 seconds.
Remove the rag or sponge from the bucket and wring out any excess vinegar.
Place the vinegar-soaked rag or sponge onto the rust stain and let it lie on the stain for 30 minutes.
Scrub the rust stain vigorously until it is gone. You may have to re-dip the rag in the vinegar to remove any left-over fragments of rust.
Wipe the plastic with a clean damp sponge.
Dry the plastic with a clean dry rag.
If the rust stain on the plastic is large or old, use several vinegar-soaked rags to cover the stain. Let the rags stay on the rust stain for an hour or two before you start removing the rust.