I picked up three free 55 gallon plastic drums after seeing them posted on craigslist. I was inspired by the compost tumbler and rain collection instructables, and I was looking to build my own. However, the plastic drums contained an industrial grade detergent used in food and beverage processing facilities. Two of the barrels were FiChlor Foam HD and the other contained Liqualin CC. Do you think I could clean these out enough to make them safe for these projects? Would the chemicals have leaked into the plastic? For rain collection, I was going to use the water for flushing my toilet, so it wouldn't be for watering a garden, and definitely not for drinking. For the compost, would the chemicals remaining in the plastic leak into the compost? And then would any plants exposed to that compost die? I really appreciate some feedback on this. I've read most instructables on here that involve 55 gallon plastic drums, and the recommendation is to use Food Grade containers. I'm just disappointed about the possibility of not being able to use the ones I picked up because they contained a detergent. The containers are marked as "Corrosive" and "Do not reuse this container unless it is first professionally cleaned and reconditioned." This is definitely a bad sign. :( Thanks guys, Eoin Here's some information I found from the manufacturer, Chemetall: Safety and Handling Precautions: Oakite FiChlor Foam HD is a highly alkaline chlorinated material containing sodium and potassium hydroxide. Direct contact causes irritation of eyes and skin. It is harmful if swallowed. Avoid contact with eyes, skin and clothing. Wear safety goggles, rubber gloves and other protective clothing when handling. Wash thoroughly after handling. Avoid breathing vapors. Use only in well-ventilated areas. Do not take internally. Liqualin CC: Heavy-duty, low foaming, non-silicated alkaline liquid for use in CIP systems or spray washing stainless steel processing equipment in beverage and food plants.