http://www.virtualweberbullet.com/plastics.html
Scroll to bottom
==============
Since HDPE buckets are somewhat porous, they can hold odors and stains from foods like pickles or barbecue sauce. If you score a free bucket from a restaurant, try this cleaning routine suggested by USA Emergency Supply. It has worked pretty well for me.
Wash the bucket inside and out with warm, soapy water, then rinse.
Place the bucket outside in a sunny location.
Pour 1 cup of baking soda into the bucket and fill with warm water all the way to the top. Stir to dissolve, then put on the lid, or cover with aluminum foil.
Let the bucket sit in the sun for several days, then empty and rinse out.
Pour 1 cup of bleach into the bucket and fill with warm water all the way to the top. Stir to mix, then put on the lid, or cover with aluminum foil.
Let the bucket sit in the sun for several days, then empty.
Wash again inside and out with warm water and dishwashing liquid, then let dry with the lid off.
============