We are using a used steel drum barrel as a rainwater container. Someone else in our house brought it from work, and we haven't bothered replacing with a plastic one yet.

Supposing that there is no harmful residue of the previous content in it: It is rusting a bit on the inside, so the water doesn't look that clean. Is the iron oxide actually harmful for vegetables? We are using it to irrigate plants such as peppers, salad, strawberries and some herbs.

2 Answers 2


Rust is iron oxide, which does not harm plants in moderate amounts, because it is not water soluble unless the soil ph is very low. In fact, oxidized iron is what gives most red subsoils their color.

Watering your plants with this water will not harm them at all. If you suppose there was nothing environmentally harmful in it before (which is NOT a good idea if you really don't know, because many things stored in steel barrels are not good for soil, and rust is very absorbent), then go ahead and use it. I would ask your friend if he/she wouldn't mind finding out what the barrel was used for.

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    Ah, thanks for the point about the soils and the details! As to the content, I'll make sure to double-check. And I'll remind him of his offer to powder-coat the barrel from the inside, just to make sure :-)
    – anderas
    Commented May 22, 2014 at 7:39

This info is not totally true. Although the rust is not harmful, if you are planning to use it to water vegetables, it will leave an unwanted taste. Because of the metal and rust in the bin, your plants will grow and have a more salty flavor.

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    What you are saying is not true. Plants will use whatever iron they need to produce their own food and seed the rest stays in the soil. Iron is not salty. Iron tastes like iron.
    – stormy
    Commented Sep 27, 2015 at 20:29
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    This reads somewhat as a comment on the other answer, but if it's to stand as an answer in its own right, you'll need to provide more information as to why the other answer is incorrect.
    – Niall C.
    Commented Sep 27, 2015 at 21:18

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